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UNIVERSITY  OF  ILLINOIS. 


UNIVERSITY  OF  ILLINOIS 

Agricultural  Experiment  Station 


BULLETIN    NO.    95. 


THE   MORE   IMPORTANT  INSECT 
INJURIES  TO   INDIAN   CORN. 

GENERAL  INTRODUCTION  TO  THE  SUBJECT,  AND  DISCUSSION  OF  INSECTS 
INJURIOUS  TO  THE  PLANT  ABOVE  GROUND. 


BY  S.  A.  FORBES, 
STATE  ENTOMOLOGIST. 


URBANA,  ILLINOIS,  NOVEMBER,   1904. 


SUMMARY  OF  BULLETIN  No.  95. 

1.  The  corn  insects  as  a  group.  Pages  33 1,332 

2.  Divisions  of  the  corn-insect  group.  Page  332 

3.  Adaptations  and  reactions  of  the  corn  plant  to  its  insect  visitants.   Page  333 

4.  General  effects  of  insect  injury.     With  the  exception  of  injury  to  the 
ear,  the  effect  of  bisect  injury  is  essentially  a  starvation  effect.  Page  335 

5.  Any  management  which  helps  to  maintain  and  strengthen  the  plant  will 
lessen  or  prevent  losses  from  insect  injury.  Page  336 

6.  General    description    of    injuries    to    the    leaves,    to    the  stalk,  and    to 
the  ear.  Pages  336-338 

7.  General    discussion    of     in  juries    to    corn    by    the    different    orders    of 
insects.  Pages  338-344 

8.  The   corn   insects  grouped   or  divided  into  "  the  more  important,"  "  the 
less  important,"  and  "the  unimportant"  species.  Page  344 

9.  Synopsis  of   injuries   by   the  more  important  insects  which   injure  the 
plant  above  ground.  Page  346 

10.  The  corn  cutworms.     Twelve  species  discussed.  Pages  347-366 

11.  The  sod  web-worms,  or  root  web-worms.     Six  species  discussed. 

Pages  366-374 

12.  The  burrowing  web-worms.  Page  374 

13.  The  stalk-borer.  Page  374 

14.  The  army-worm.  Page  377 

15.  The  corn  bill-bugs.     Eight  species  discussed.  Pages  382-387 

16.  The  chinch-bug.  Page  387 

17.  The  grasshoppers.  Page  394 

18.  The  ear-worm  or  corn-worm.  Page  397 

19.  Reference  to  articles  in  the  Eighteenth  Report  of  the  Illinois  State  Ento- 
mologist and  in  Station  Bulletin  44,  for  a  discussion  of  insects  affecting  the  seed 
and  roots  of  Indian  corn.  Page  399 


THE    MORE    IMPORTANT    INSECT    IN- 
JURIES   TO    INDIAN    CORN.* 

BY  S.  A.  FORBES,  STATE  ENTOMOLOGIST. 

The  Illinois  State  Entomologist  is  by  law  required  to  investigate 
"the  entomology  of  Illinois,"  and  particularly  to  study  "the  history  of 
the  insects  injurious  to  the  products  of  the  horticulturists  and  agricul- 
turists of  the  state,"  and  to  prepare  "reports  of  his  researches  and  dis- 
coveries in  entomology  for  publication  by  the  state."  While  the  main 
end  of  his  studies  should  thus  be  economic,  the  whole  subject  of  the 
entomology  of  Illinois  is  nevertheless  open  to  his  investigation  and 
report.  The  advancement  of  entomology  as  a  science  and  the  adap- 
tation of  entomological  knowledge  to  educational  uses,  if  not  his  duty, 
are  clearly  within  the  general  field  of  his  privilege.  I  have  accordingly, 
in  the  preparation  of  this  report,  taken  into  especial  account  the  rapidly 
rising  interest  in  nature  study  as  a  useful  feature  of  the  work  of  the 
elementary  school,  and  I  have  availed  myself  of  the  opportunity  to 
incorporate  into  the  present  discussion  much  matter  of  little  or  no 
economic  interest,  but  worthy  of  presentation,  nevertheless,  as  material 
of  value  to  the  public  school  teacher  in  search  of  information  concerning 
the  commoner  objects  of  his  neighborhood. 

The  corn  plant  is  so  conspicuous  a  feature  in  the  agriculture,  and 
hence  in  the  civilization,  of  Illinois,  that  it  must  always  be  an  attractive 
subject  of  study  to  the  youth  of  the  state,  and  suitable  in  a  multitude 
of  cases  for  use  in  the  public  schools.  Like  most  of  the  larger  and  more 
abundant  plants,  it  draws  to  itself  a  considerable  assemblage  of  insects 
which  find  in  it  various  attractions  and  advantages  contributing  to 
their  maintenance  or  their  pleasure,  and  which  thus,  by  their  common 
interest  in  this  one  great  plant,  come  to  form  a  kind  of  associate  group, 
the  group  of  the  corn  insects.  Very  few  of  them  are  peculiar  to  the  corn 
plant  alone,  since  nearly  all  of  them  are  equally  or  even  more  strongly 
attracted  to  other  plants  as  well.  Many  of  them,  indeed,  belong  to  a 
considerable  number  of  such  plant-insect  groups,  visiting  or  living  on 
many  other  plant  species,  cultivated  and  wild. 

Not  one  of  them  is  immediately  beneficial  to  the  corn  plant  itself, 

*This  article  contains  the  introduction  and  the  first  division  of  the  Twenty- 
third  Report  of  the  Illinois  State  Entomologist.  The  remaining  divisions  of  that 
report  are  devoted  to  the  less  important  and  the  relatively  unimportant  corn 
insects. 

331 


332  BULLETIN  No.  95.  [November. 

although  a  considerable  number,  parasitic  or  predaceous  on  other 
insects,  are  indirectly  beneficial  to  it  by  relieving  it  to  some  extent  from 
the  attacks  of  insect  enemies.  Several  of  them  do  no  appreciable  harm 
at  any  time;  others  are  injurious  only  under  special  conditions  more  or 
less  rare;  and  still  others  are  injurious  to  it  whenever  and  wherever  they 
occur.  Their  common  interest  in  this  one  plant  of  course  brings  these 
insects  also  into  important  relations  to  each  other,  like  those  which 
influence  any  local  assemblage  of  animals — those  of  a  pond,  of  a  grove, 
or  of  a  barnyard,  for  example — and  make  of  them  a  related  group  instead 
of  a  mutually  indifferent  assemblage. 

It  is  the  object  of  the  present  report  to  discuss  this  entire  group  of 
corn  insects,  to  the  end  that  the  teacher  and  student,  of  whatever  grade, 
may  find  in  this  paper  a  clue  to  the  whole  system  of  insect  life  of  which 
the  corn  plant  is  the  center.  The  study  here  presented  may  thus  stand 
as  in  many  respects  a  type  or  example  of  the  relations  of  a  plant  to  its 
insect  visitants.  While  in  this  treatment  the  economic  features  of  the 
system  will  receive  full  attention,  this  will  not  be  to  the  exclusion  of 
features  of  scientific  or  educational  interest  merely;  but  to  avoid  encum- 
bering the  more  important  economic  matter  with  details  and  discussions 
of  secondary  interest,  the  paper  is  divided  into  sections,  based  on  the 
economic  relation. 

DIVISIONS  OF  THE  CORN  INSECT  GROUP. 

The  entire  assemblage  of  corn  insects  is  much  too  large  and  compli- 
cated for  convenient  discussion  as  a  whole,  and  it  may  consequently 
best  be  divided  into  subordinate  groups,  some  corresponding  to  .the 
different  organs  and  structures  of  the  corn  plant  itself,  others  to  different 
stages  of  its  growth,  and  still  others  to  the  previous  history  of  the  land 
on  which  the  corn  is  grown  or  to  the  situation  of  the  field  with  respect 
to  other  and  adjacent  crops.  There  is,  for  example,  a  small  group  of 
insects  which  become  abundant  in  corn-fields  only  where  corn  is  grown 
on  the  same  ground  year  after  year — the  corn  root-worm  is  an  instance — 
while  others,  like  the  wireworms,  infest  corn  injuriously  only  when  this 
follows  within  a  year  or  two  upon  grass,  and  others,  like  the  stalk-borer, 
may  invade  corn  only  from  grass-lands  outside.  The  corn  root-aphis 
makes  its  main  attack  on  the  crop  while  the  plant  is  young,  and  the 
leaf-aphis  usually  does  not  appear  until  the  crop  is  well  advanced,  and 
continues  in  rapidly  increasing  numbers  until  frosty  weather  checks  its 
multiplication. 

Among  the  groups  corresponding  to  the  different  parts  and  organs  of 
the  growing  plant  the  most  definite  distinction  is  between  those  especially 
adapted  to  a  life  under  ground,  and  those  which  never  enter  the  earth 
in  search  of  food.  The  white  grubs,  wireworms,  corn  root-worms,  seed- 
corn  maggots,  and  root-lice  are  on  one  side  of  this  dividing  line,  and  the 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  333 

chinch-bug,  army- worm,  corn-worm,  leaf-louse,  and  a  host  of  additional 
species  are  on  the  other.  Among  the  subterranean  corn  insects  we  may 
distinguish  a  few  which  feed  only  on  the  softened  seed  in  the  earth; 
others  confined  to  the  living  roots;  other  root  insects  which  may  extend 
their  injuries  to  the  underground  part  of  the  stalk;  and  still  others  which 
may  also  eat  the  seed. 

While  the  relations  of  the  injurious  species  of  corn  insects  to  the 
plant  thus  differ  widely,  making  it  possible  to  divide  the  species  accord- 
ing to  these  relations,  groups  so  formed  are  by  no  means  as  definite  and 
sharply  limited  as  those  in  a  classification  based  on  form  and  structure, 
but  they  overlap  and  intermingle  variously,  and  may  even  undergo 
radical  change  with  the  lapse  of  time— a  change  corresponding  to  a 
change  of  habit  in  a  species  with  the  changing  conditions  around  it. 
This  is  merely  saying  in  other  words  that  the  actions,  behavior,  habits, 
and  preferences  of  insects  are  more  flexible  and  variable  and  far  more 
readily  adaptable  than  such  of  their  structures  as  are  used  in 'their- 
classification. 

ADAPTATIONS  AND  REACTIONS  OF  THE  CORN  PLANT  TO  ITS 
INSECT  VISITANTS. 

There  is  little  in  the  structure  or  the  life  history  of  the  corn  plant  to 
suggest  any  special  adaptation  to  its  insect  visitants — no  lure  to  insects 
capable  of  service  to  it,  or  special  apparatus  of  defense  against  those 
especially  liable  to  injure  it.  The  fertilization  of  its  seed  is  fully  pro- 
vided for  without  reference  to  the  agency  of  insects,  and  would  be  as 
well  accomplished  if  none  of  them  ever  carried  pollen  from  the  tassel  of 
one  plant  to  the  silk  of  another.  Hence  the  plant  secretes  no  honey 
and  has  no  floral  odor  or  colored  bloom.  It  has  no  armature  of  spines 
or  bristly  hairs  to  embarrass  the  movements  of  insects  over  its  surface 
or  to  defend  against  their  attack  the  softer  and  more  succulent  foliage  at 
its  growing  tip.  It  secretes  no  viscid  fluids  to  entangle  them,  and  forms 
no  chemical  poisons  or  distasteful  compounds  in  its  tissues  to  destroy  or 
repel  them.  The  cuticle  of  its  leaf  is  neither  hardened  nor  thickened  by 
special  deposits;  its  anthers  are  neither  protected  nor  concealed;  and  its 
delicate  styles — the  silks  at  the  tip  of  the  ear — are  as  fully  exposed  as  if 
they  were  the  least  essential  of  its  organs.  Minute  sucking  insects  are 
able  at  all  times  to  pierce  its  roots  and  its  leaves  with  their  flexible  beaks, 
and  with  the  single  exception  of  its  fruit  there  is  no  part  of  it  which  is 
not  freely  accessible  at  any  time  to  any  hungry  enemy.  Only  the  kernel, 
which  was  lightly  covered  in  the  wild  corn  plant  by  a  single  chaffy  scale 
or  glume,  has  become,  in  the  long  course  of  development,  securely  inclosed 
beneath  a  thick  coat  of  husks,  impenetrable  by  nearly  all  insects;  and 
we  may  perhaps  reasonably  infer  that  among  the  possible  injuries 


;i'U  BULLETIN    No.  95.  [November. 

against   which   this  conspicuous  protective  structure'   defends   the  soft 
young  kernel  those  of  insects  are  to  he  taken  into  account. 

There  arc  also,  of  course,  many  insect  species,  even  among  those 
which  habitually  frequent  the  plant,  which  are  unable  to  appropriate 
certain  parts  of  its  substance  to  their  use,  but  this  is  because  of  the 
absence  of  adaptation  on  their  part  and  not  because  of  any  special 
defensive  adaptation  on  the  side  of  the  plant.  The  adult  or  beetle  of  the 
corn  root-worm  (Diabrotica  longicornis)  is  an  example.  The  larva  of 
this  insect  feeds  only  on  the  roots  of  corn,  and  the  beetles  consequently 
all  make  their  first  appearance  for  the  year  in  corn-fields,  and  find  their 
food  at  first  on  the  corn  plant.  Owing,  however,  to  the  weakness  of 
their  jaws  they  are  unable  to  eat  the  leaves  of  corn,  and  feed  only  on  the 
fallen  pollen  and  the  young  silks  just  growing  out  from  the  husks. 
Later,  as  the  pollen  disappears  and  the  silk  dries  up,  they  are  driven  to 
other  plants,  or  even  compelled  to  leave  the  field  entirely  in  search  of 
food,  and  hence  are  found  at  that  time  on  clover  heads  and  on  the  flowers 
of  thistles  and  ragweed  and  other  late-blooming  plants. 

Thus  we  may  say  that  with  the  exception  of  the  ear  the  whole  plant 
lies  open  and  free  to  insect  depredation,  and  that  it  is  able  to  maintain 
itself  in  the  midst  of  its  entomological  dependents  only  by  virtue  of  its 
unusual  power  of  vigorous,  rapid,  and  superabundant  growth.  Like 
every  other  plant  which  is  normally  subject  to  a  regular  drain  upon  its 
substance  from  insect  injury,  it  must  grow  a  surplus  necessary  for  no 
other  purpose  than  to  appease  its  enemies;  and  this,  in  a  favorable  season, 
the  corn  plant  does  with  an  energetic  profusion  unexampled  among  our 
cultivated  plants.  Insects,  indeed,  grow  rapidly  as  a  rule,  but  soon 
reach  their  full  .size.  Many  species  multiply  with  great  rapidity,  but 
even  these  the  corn  plant  will  outgrow,  if  given  a  fair  chance,  provided 
they  are  limited  to  corn  itself  for  food. 

The  great  injuries  to  corn  by  insects  are  done  by  species  which  come 
into  it  from  other  and  earlier  crops;  insects  which  are  in  the  full  tide  of 
their  multiplication,  or  perhaps  at  their  maximum  number  for  the 
season,  while  the  corn  plant  is  still  small  and  young.  It  is  not  the  corn 
root-aphis  which  injures  corn  most  seriously,  although  confined  to  the 
corn  plant  and  endowed  with  a  power  of  multiplication  scarcely  sur- 
passed among  insects;  it  is  the  chinch-bug,  which  breaks  into  the  field 
of  young  corn  from  adjoining  wheat  or  oats,  where  it  has  already  in- 
creased a  hundredfold  since  spring  began;  it  is  the  army-worm  or  the 
cutworms  or  the  wireworms  or  the  white  grubs,  which  began  and  got 
most  of  their  growth  in  grass,  and  now,  by  their  numbers  and  voracity, 
overwhelm  the  young  corn  before  the  time  of  its  most  rapid  growth  has 
arrived.  Practically  limited  to  this  vigor  of  growth  as  a  means  of 
escape  from  insect  attack,  anything  which  checks  or  retards  its  growth 
for  a  considerable  time  has,  of  course,  the  effect  to  increase  insect  injury. 


I '.»()  1. 1  INSKCT    LN.MJKIKS   TO   INDIAN    COHX.  335 

Thus,  a  cold  and  backward  spring  after  corn-planting  increases  injury  to 
the  seed  and  the  young  plant  by  wireworms,  seed-corn  maggots,  and  the 
corn  root-aphis;  and  a  midsummer  drouth  greatly  increases  the  effect, 
if  not  the  amount,  of  injury  by  chinch-bugs,  white  grubs,  and  the  corn 
root- worm. 

GENERAL  EFFECTS  OF  INSECT  INJURY. 

With  few  exceptions,  the  effects  of  injury  to  corn  by  insects,  where 
they  do  not  amount  to  a  total  destruction  of  the  plant,  may  be  compared 
to  the  effects  of  simple  starvation.  Anything  which  lessens  the  store 
of  food  laid  up  in  the  corn  kernel  for  use  in  germination  and  early  growth, 
or  damages  seriously  the  roots  or  the  leaves,  or  draws  away  the  sap 
before  it  has  served  its  purpose  in  the  plant,  practically  amounts  to  a 
diminution  of  the  available  food  supply.  An  impoverished  soil,  very 
dry  weather,  the  sapping  of  the  cells  and  vessels  of  the  plant  by  sucking- 
insects,  destruction  of  any  considerable  part  of  its  roots,  and  the  dead- 
ening or  destruction  of  any  large  percentage  of  its  leafage,  all  have 
similar  consequences,  which  may  be  classed  as  starvation  effects,  and 
when  two  or  more  of  them  coincide,  each  serves,  of  course,  to  intensify 
the  effects  of  the  others. 

One  common  result  of  these  starvation  injuries  to  corn  is  the  failure 
of  the  plant  to  form  the  ear;  the  stalk  itself,  perhaps,  making  a  fairly 
vigorous  growth,  but  remaining  barren,  and  hence  useless  except  for 
fodder.  Injury  to  the  roots,  if  continuous  and  severe,  has,  however, 
another  effect,  of  a  more  special  character,  in  so  weakening  the  hold  of 
the  plant  on  the  earth  that  the  stalk  readily  falls  after  it  has  become  top- 
heavy  with  growth,  and  is  not  able  to  rise  again.  This  happens  after 
soaking  rains  have  softened  the  ground,  especially  if  accompanied  by 
heavy  winds.  It  is  sometimes  a  consequence  of  the  destruction  of  the 
roots  by  the  corn  root-worm  and  the  white  grubs,  and  is  sometimes 
due  to  chinch-bugs,  which,  by  sucking  the  sap  from  the  base  of  the 
stem,  prevent  the  formation  of  the  strong  "brace-roots" — the  upper 
circle  of  roots— put  forth  during  the  last  stages  of  the  growth  of  the 
stalk.  Actual  loss  of  roots  sometimes  also  delays  the  development  of 
the  plant,  acting  in  this  respect  like  an  unusually  cool  summer.  Thus, 
a  field  infested  by  grubs  or  root-worms  may  remain  green  after  unin- 
jured fields  are  practically  ripe.  Such  backward  fields  are  especially 
exposed  to  injury  by  frosts,  and  hence  are  likely  to  yield  an  unusual 
amount  of  soft  corn. 

Besides  this  class  of  general  injuries,  which  diminish  the  vitality  and 
lessen  the  size  or  delay  the  growth  of  the  whole  plant,  there  remain  only 
the  more  local  injury  to  the  ear,  caused  almost  wholly  by  the  caterpillar 
known  as  the  corn  root-worm,  and  the  damage  done  to  the  ear  in  the 
crib  or  to  the  kernel  in  the  bin  by  the  weevils  and  other  insects  of  similar 


336  BULLETIN   No.  95.  [November, 

habit.  With  respect  to  their  economic  mischief,  there  is  probably  little 
to  choose  between  those  insects  which,  by  destroying  or  weakening  the 
plant,  prevent  the  development  of  the  ear  or  diminish  its  size  and  those 
which  destroy  the  mature  product.  One  deprives  the  farmer  of  the 
reward  of  his  labors  and  investments  as  completely  as  the  other. 

GENERAL  MEASURES  OF  PREVENTION  AND  REMEDY. 

From  what  has  been  said  above  with  respect  to  the  starvation  effect 
of  most  insect  injuries,  it  follows  that  any  management  which  helps  to 
maintain  and  strengthen  the  plant  by  furnishing  it  better  or  more 
abundant  food  will  lessen,  or  perhaps  wholly  prevent,  losses  from  insect 
injury  which  must  otherwise  be  serious  or  complete.  A  strong,  rich  soil, 
well  cultivated,  well  watered,  and  well  drained,  may  grow  a  good  crop 
notwithstanding  an  amount  of  infestation  by  chinch-bugs,  root-lice,  root- 
worms,  and  white  grubs  which  would  be  fatal  on  poor  or  poorly  managed 
land.  The  good  corn  farmer  may  thus  escape  with  a  profitable  yield  under 
insect  attacks  which  will  leave  his  less  intelligent  or  less  careful  brother 
in  debt  after  his  crop  is  harvested.  This  is  not  merely  because  the 
vigorous  plant  will  easily  support  an  amount  of  injury  under  which  the 
unthrifty  one  will  suffer  or  succumb.  It  is  an  established  fact  that 
many  insects  themselves  will  not  thrive  as  well  or  multiply  as  rapidly 
on  a  vigorous,  quickly  growing  plant  as  on  one  in  feeble  condition. 

More  special  measures  are  a  proper  rotation  of  crops,  such  that  corn 
shall  not  be  exposed  to  injury  by  insects  which  have  bred  on  the  same 
ground  the  preceding  year,  either  in  other  crops  or  in  corn  itself;  timely 
plowing,  to  forestall  the  breeding  of  insects  by  destroying  them  or  their 
food ;  timely  planting,  with  reference  to  the  period  of  the  greatest  abun- 
dance or  greatest  activity  of  certain  species;  and  the  use  of  barriers 
against  the  movement  of  certain  destructive  species  into  the  corn  from 
fields  adjacent,  combined  with  insecticide  measures  against  hordes  or 
companies  of  destructive  insects,  which  if  left  to  themselves  will  work 
great  and  immediate  harm. 

INSECT  INJURIES  TO  DIFFERENT  PARTS  OF  THE  CORN  PLANT. 

To  the  Leaves. — That  the  abundant,  conspicuous,  and  easily  accessible 
foliage  of  the  corn  plant  should  attract  a  large  number  of  hungry  insects 
and  suffer  more  from  their  attentions  than  any  other  part,  is  naturally 
to  be  expected,  since,  as  a  consequence  of  its  gradual  and  long-continued 
growth,  it  offers  for  consumption  during  many  months  the  most  succu- 
lent and  nourishing  food  which  the  plant  produces. 

More  than  one  hundred  species  of  insects,  representing  all  of  the 
orders  injurious  to  corn,  have,  in  fact,  been  found  feeding  on  the  leaves. 
The  most  important  differences  in  their  injuries  are  due  to  differences  in 
the  mouth-parts  of  the  insects — whether  sucking  or  biting — and  the 


1904.]  INSECT  INJURIES  TO  INDIAN  CORN.  337 

principal  differences  subordinate  to  these  are  due  to  differences  in  size, 
number,  and  feeding  habits  of  the  insects  concerned. 

A  sucking  insect,  merely  piercing  the  tissue  with  the  delicate  bristle- 
like  structures  of  its  beak  and  withdrawing  from  the  adjacent  parts  the 
more  fluid  portions  of  the  cell  contents,  may,  if  very  small,  drain  and 
deaden  only  a  few  neighboring  cells,  thus  causing  a  minute  discolored 
speck,  insignificant  unless  these  injuries  are  very  numerous.  Such  are 
the  injuries  done  by  leaf -hoppers  and  others  minute  sucking  species  of 
active  habit,  each  deadened  speck  evidently  representing  a  single  meal 
of  the  insect,  which  moves  to  another  point,  or  perhaps  to  another  plant, 
for  its  next.  Plant-lice,  on  the  other  hand,  which  change  their  location 
with  difficulty  and  reluctance,  each  remaining,  as  a  rule,  about  where  it 
was  born,  accumulate  in  patches  or  colonies  as  they  multiply,  and, 
closely  occupying  a  larger  surface,  so  concentrate  their  injury  as  to  do 
much  more  serious  damage.  If  injuries  of  this  sort  are  greatly  multi- 
plied, as  by  multitudes  of  the  chinch-bugs,  the  whole  leaf  is  killed  outright. 

Gnawing  and  biting  insects  differ  similarly  with  respect  to  the  mag- 
nitude and  seriousness  of  their  injuries.  Some  of  the  small  size  with 
feeble  biting  organs  merely  gnaw  away  the  more  superficial  and  softer 
parts  of  the  leaf,  leaving  the  vein  structures  untouched,  and  causing 
discolored  specks  not  unlike  those  due  to  leaf-hoppers;  somewhat  larger 
kinds  make  small  holes  through  the  leaf  like  pin-pricks  or  shot-holes; 
and  still  larger  ones,  such  as  grasshoppers,  eat  away  the  edge  of  the  leaf 
or  gnaw  large  and  irregular  holes  through  it,  avoiding  nothing  but  the 
heavy  midrib  and  the  stronger  veins.  Grasshoppers  sometimes  strip  the 
whole  leaf  to  the  midrib,  and  eat  away  all  but  the  tougher  and  thicker 
part  of  this. 

Curious  parallel  rows  of  precisely  similar  holes,  running  across  the 
corn  leaf,  are  made  by  the  corn  bill-bugs,  which  thrust  their  stiff 
snouts,  or  "bills,"  into  the  young  plant  where  its  leaves  are  rolled  together, 
and  eat  out  the  interior  by  means  of  minute  jaws  borne  at  the  tip  of  the 
snout. 

To  the  Stalk. — The  stalk  of  the  plant  is  injured  by  the  loss  of  sap 
drained  away  by  sucking  insects,  of  which  the  chinch-bug  is  the  most 
destructive;  by  a  mining  of  its  interior  by  caterpillars,  like  the  stalk- 
borers,  which  enter  it  from  the  outside;  by  the  punctures  and  feedings 
of  the  corn  bill-bugs,  which  sink  their  beaks  into  its  substance  and  eat 
out  its  soft  interior  tissue;  and  by  the  gnawing  of  a  few  larger  beetles 
(Ligyrus,  Allorhina,  etc.),  which  eat  out  large  cavities  in  its  side.  It  is 
similarly  gnawed  and  irregularly  eaten,  when  young,  by  sod  web-worms; 
it  is  cut  off  at  or  near  the  ground  by  cutworms,  and  in  rare  instances 
by  ants  (Pogonomyrmex  barbatus);  and  devoured,  with  the  rest  of  the 
young  plant,  by  army-worms  and  garden  web-worms.  Under  ground  it 
may  be  gnawed  out  or  eaten  through  from  side  to  side  by  wireworms, 


338  BULLETIN    No.  l)f>.  \Norcntber. 

or  irregularly  mined  by  the  small,  soft-bodied  larva  known  as  the  southern 
corn  root-worm  (Diabrotica  1 .--pundata) . 

To  the  Ear. — Injuries  to  the  ear  are  of  two  principal  kinds:  the  kernels 
may  be  eaten  beneath  the  husk  by  a  large  green  or  striped  caterpillar 
which  bores  in  from  the  outside  and  feeds  irregularly  about,  fouling  the 
ear  with  its  excrement;  or  the  silks  may  be  gnawed  away  from  the  tip 
of  the  cob  at  a  time  to  interfere  with  the  process  of  fertilization,  and 
thus  to  blight  the  kernel.  Small  damage  is  also  done  by  various  beetles, 
caterpillars,  and  grasshoppers,  which  gnaw  away  the  kernels  at  the  tip 
of  the  ear  where  these  are  exposed  by  the  opening  of  the  husks.  This 
injury,  however,  is  mainly  confined  to  ears  upon  the  ground  or  to  those 
which  have  been  previously  visited  by  birds.  Sometimes  the  husks  are 
largely  eaten  away  by  grasshoppers,  together  with  the  softer  parts  of  the 
young  ear  itself. 

INJURIES  TO  CORN  BY  THE  DIFFERENT  ORDERS  OF  INSECTS. 

Hymenoptera:  Bees,  Wasps,  Ants,  etc. — With  the  exception  of  a  small 
bee  (Halictus  lerouxi)  frequently  seen  gathering  corn  pollen  from  the  silk, 
leaves,  and  husks,  but  responsible  for  neither  injury  nor  benefit  to  the 
plant,  various  kinds  of  ants  are  the  only  insects  of  this  order  which  occur 
frequently  in  fields  of  corn. 

Ants  are  among  the  most  active,  observant,  and  capable  of  all  insects. 
Their  restless  and  wide-ranging  habits  bring  them  into  acquaintance 
with  every  variety  of  objects  in  their  neighborhood,  and  little  escapes 
their  notice  or  their  appropriation  which  can  in  any  way  be  converted 
to  their  support.  The  abundance  of  certain  species  in  corn-fields  in 
spring,  shown  especially  by  their  burrows  in  and  near  the  hills  of  corn, 
is  a  matter  of  common  observation.  Even  in  fall  after  frost,  or  during 
the  warmest  days  of  an  open  winter,  these  enterprising  rangers  may  be 
seen  climbing  over  the  dead  stalks  or  coursing  irregularly  about  upon 
the  bare  earth;  and  many  of  them  pass  the  winter  in  burrows  or  nests 
among  the  corn  roots,  where  they  are  turned  out  in  the  spring  plowing 
with  eggs  and  larvse  in  their  possession. 

A  few  corn-field  ants  are  directly  injurious  to  corn  by  hollow- 
ing out  the  softened  and  sprouting  kernels  in  the  earth,  thus  either  pre- 
venting its  germination,  killing  the  young  shoot,  or  weakening  it  by 
appropriating  the  stored  food  necessary  to  its  earliest  growth.  The  com- 
mon house-ant  has  been  once  or  twice  reported  to  gnaw  the  young  corn 
leaf  and  drink  the  sap  exuding  from  the  wounds  thus  made.  One  species 
of  southern  leaf-cutting  ant  bites  out  pieces  of  the  corn  leaf,  which  it 
carries  away  to  its  underground  burrows,  and  certain  other  ants  are 
found  occasionally  about  the  tips  of  the  green  ear  feeding  on  kernels 
which  have  been  injured  previously  by  other  insects  or  by  birds. 

Direct  injuries  of  this  class  are,  on  the  whole,  economically  insig- 


HMM.|  INSERT   INJURIES  TO   INDIAN    CORN.  31-50 

nificant,  but  a  few  kinds  of  ants  are  capable  of  an  indirect  injury  to  corn 
which  often  becomes  extremely  serious.  By  the  care  and  assistance  given 
to  plant-lice,  or  aphides,  which  infest  the  roots  and  leaves  of  corn,  they 
greatly  extend  and  increase  the  injury  done  by  these  insects  which  they 
have  in  charge.  This  injury  is  mainly  due  to  ants  which  live  in  corn- 
fields throughout  the  year,  reinforced  as  they  are  by  newcomers  from 
adjacent  grass-lands  in  early  spring.  In  their  underground  nests  in  the 
field  they  collect  in  fall  the  eggs  of  the  corn  root-aphis,  and  in  spring 
they  place  the  young  hatching  from  these  eggs  on  the  roots  of  suitable 
food-plants.  As  these  grow  and  multiply,  the  ants  transfer  them  from 
one  plant  to  another  as  necessity  may  arise,  devoting  themselves  to  their 
welfare  with  a  constancy  and  patience,  due  not  to  charity,  as  it  might 
seem,  but  to  an  enlightened  regard  for  their  own  best  interests.  Through- 
out nearly  the  whole  season,  indeed,  these  ants  are  dependent  on  their 
helpless  charges  for  food,  which  they  find  in  the  abundant  fluids  given  off 
by  the  plant-lice  as  these  suck  the  sap  from  the  growing  plant. 

To  the  ant  the  plant-lice  are  living  automatic  pumps,  constantly 
drawing  from  the  tissues  of  the  plant  excessive  quantities  of  sap,  abstract- 
ing from  this  only  a  part  of  its  food  material  as  it  passes  through  their 
bodies,  and  giving  it  forth  again  in  condition  to  serve  a  second  time  for 
the  support  of  insect  life.  A  similar  benefit  is  derived  by  other  species 
of  ants  from  the  corn  leaf-aphis,  but  this  insect  is  only  slightly  injurious 
to  corn,  and  the  ants  are  less  essential  to  it.  Nothing  is  known,  for 
example,  to  indicate  that  the  eggs  of  the  leaf-aphis  are  cared  for  by  ants, 
and,  indeed,  no  eggs  of  this  species  have  ever  been  found. 

With  the  exception,  therefore,  of  the  various  species  of  ants  which 
attend  the  corn  root-louse  in  the  earth,  injuries  to  corn  by  these  insects 
may  be  practically  ignored  as  insignificant,  and  at  worst  as  not  serious 
enough  to  require  or  warrant  attempts  at  measures  of  prevention. 

Diptera:  Flies  and  Gnats. — Among  the  multitudes  of  two-winged 
flies,  or  Diptera,  only  a  few  are  found  frequently  on  or  about  the  corn 
plant,  and  scarcely  one  of  these  is  likely  to  do  it  any  serious  injury. 
The  winged  insects  themselves  are  never  injurious  to  corn,  all  the  harm 
done  by  these  insects  to  this  plant  being  through  their  larvae  or  maggots 
only.  When  corn  has  followed  upon  clover,  the  roots  of  the  young  plant 
have  rarely  been  injured  by  the  large,  dirty-looking,  grub-like  larvae  of 
one  or  two  of  the  crane-flies  (Tipulidce) ;  the  planted  seed  is  sometimes 
eaten  to  some  extent  by  the  small  seed-corn  maggot  (Pegomi/ia  fuscipes) ; 
the  leaves  are  occasionally  mined  in  a  very  small  way  by  two  or  three 
mining  maggots  (Diastata  and  Odontocera  dorsalis);  and  the  larva  of  a 
Syrphus  fly,  which  commonly  feeds  on  the  fallen  pollen  lodged  in  the 
tassel  or  at  the  tip  of  the  ear  or  at  the  base  of  the  leaf,  is  reported  some- 
times to  puncture  the  leaf  for  the  sake  of  the  sap.  Other  Syrphus  larva1 


340  BULLETIN   No.  95.  [November, 

doubtless  compensate  fully  for  these  small  injuries  by  feeding  on  the 
corn  leaf-aphis,  of  which  they  are  very  fond. 

The  sole  measure  of  prevention  suggested  by  these  facts  relates  to 
the  so-called  meadow  maggots,  the  tipulid  larvae  mentioned  above. 
These  insects  are  found  in  injurious  numbers  only  in  meadow-lands 
where  they  have  hatched  from  eggs  laid  in  grass  or  clover,  and  corn 
should  not  be  planted  on  sod  which  was  badly  infested  by  these  the  pre- 
ceding year. 

Lepidoptera:  Butterflies,  Moths,  and  Caterpillars. — Caterpillars  of 
about  fifty-six  species  have  been  collected  or  reported  from  the  corn 
plant,  feeding  on  the  stalk,  the  leaf,  and  the  ear,  or  in  some  cases  devour- 
ing the  young  plant  entire.  The  principal  injurious  groups  are  the  cut- 
worms, the  grass-worms,  the  army-worm,  the  web-worms,  the  stalk- 
borers,  and  the  so-called  corn-worm,  which  penetrates  the  husks  and 
mines  in  the  grain  beneath.  Of  these,  the  cutworms,  the  army-worm, 
and  the  corn-worm  are  by  far  the  most  destructive.  A  few  other  cater- 
pillars (Hadena  and  Prodenia),  allied  to  the  cutworms  but  having  a 
different  habit,  are  much  less  injurious. 

Some  seventeen  species  of  cutworms  have  been  taken  in  corn,  all  of 
similar  habit  with  respect  to  corn,  but  very  considerably  different  in 
life  history — a  fact  which  has  an  important  bearing  on  measures  for 
their  control. 

The  stalk-borers,  which  penetrate  the  stalk  and  burrow  within  it,  are 
the  common  species  of  that  name  (Papaipema  nitela),  the  spindle- worm 
(Achatodes  zece),  the  southern  corn-stalk-worm  or  sugar-cane  borer 
(Diatrcea  saccharalis} ,  the  smaller  corn-stalk-borer  (Elasmopalpus  ligno- 
sellus} — also  essentially  a  southern  species — and  a  caterpillar  (Helo- 
tropha  reniformis) — &  northern  species  which  does  not  injure  corn  in 
Illinois,  but  which  has  been  known  to  destroy  it  in  Michigan  by  burrow- 
ing along  the  center  of  the  young  stalk.  In  fact,  only  the  common  stalk- 
borer  is  commonly  abundant  enough  in  Illinois  to  rise  to  economic 
importance. 

The  grass-worm  (Laphygma  frugiperdd)  is  a  pest  of  common  occur- 
rence, but  is  ordinarily  economically  insignificant.  Occasionally  it  mul- 
tiplies in  here  and  there  a  place  in  a  way  to  cause  serious  mischief, 
although  it  has  but  once  been  found  by  us  (in  1889)  notably  destructive 
to  corn. 

The  army-worm  does  not  breed  in  corn-fields,  and  is  rarely  found  there 
except  when  its  numbers  force  it  to  migrate,  but  then  it  often  lays  the 
field  absolutely  bare  by  devouring  every  plant  to  the  ground.  The  turf 
web-worms  (Crambus)  are  sometimes  very  destructive  locally  in  Illinois 
to  young  corn  after  grass,  and  the  garden  web-worms  (Loxostege)  are 
even  more  injurious  in  the  west-central  states.  The  corn-worm  (Helio- 


1904.]  INSECT  INJURIES  TO   INDIAN   CORN.  341 

this  armiger),  called  also  the  cotton  boll- worm  in  the  South,  is  very 
generally  and  seriously  injurious  to  corn  in  the  ear. 

The  only  groups  of  these  caterpillars  against  which  it  is'practicable 
or  necessary  to  use  special  measures  of  protection  in  Illinois  are  the  army- 
worm,  the  cutworms,  the  web-worms,  and  the  stalk-borers,  injuries  by 
other  species  being  either  too  trivial  or  too  infrequent  to  warrant  special 
precautions,  or,  like  those  of  the  corn-worm  (Heliothis  armiger),  uncon- 
trollable by  any  measures  as  yet  devised  and  tested.  Cutworms,  web- 
worms,  and  stalk-borers  may  be  virtually  prevented  from  doing  serious 
damage  to  corn  by  a  proper  arrangement  and  rotation  of  crops,  and  by  an 
intelligent  selection  of  times  and  methods  of  handling  and  plowing  grass- 
lands previous  to  planting  them  to  corn.  The  army-worm  must  be 
excluded  from  the  field  by  barriers  to  its  progress  when  it  is  on  the  march, 
and  destroyed  as  it  collects  before  such  obstacles.  A  fuller  discussion 
of  these  various  measures  will  be  found  in  connection  with  the  special 
articles  on  the  groups  themselves. 

Coleoptera:  Beetles. — Approximately  ninety  species  of  beetles  have 
been  identified  as  corn  insects  in  either  the  larval  or  adult  stages,  a  few 
of  them  in  both.  Not  more  than  one-third  of  these  species,  however, 
need  be  mentioned  in  a  merely  economic  list,  and  if  we  do  not  attempt 
to  distinguish  for  economic  purposes  between  the  different  kinds  of 
white  grubs  and  of  wireworms  which  infest  corn  under  ground,  the  list 
so  reduced  will  contain  less  than  a  dozen  names. 

The  habits  of  the  adult  beetle  and  those  of  its  larva  are  in  most  cases 
so  widely  different  that  instances  are  few  in  which  we  find  both  stages  of 
the  same  insect  infesting  corn,  and  there  is  not  a  single  case  known  to 
me  in  which  a  similar  injury  is  done  to  corn  by  both.  The  beetle  larvae 
injurious  to  corn  all  live  under  ground,  and  their  injuries,  consequently, 
are  confined  to  the  planted  seed,  the  roots,  and  the  underground  part  of 
the  stalk.  The  adult  beetles,  on  the  other  hand,  may  eat  any  part  of  the 
plant,  from  the  seed  and  roots  to  the  silk  and  kernels  of  the  ear. 

By  far  the  most  serious  injuries  due  to  beetles  are  done  by  their 
larva?,  especially  by  those  known  as  wireworms,  white  grubs,  and  corn 
root-worms.  The  only  injuries  by  the  adults  themselves  deserving  to  be 
classed  with  these,  are  those  due  to  the  so-called  bill-bugs  of  the  genus 
Sphenophorus. 

Besides  these  major  enemies,  whose  attacks  are  largely  preventable, 
there  is  a  swarm  of  minor  or  occasional  enemies  against  which  it  is  both 
useless  and  needless  to  contend.  Several  of  the  ground-beetles  (Carab- 
idce),  for  example,  eat  the  kernel  from  the  tip  of  the  ear,  and  one  small 
abundant  species  (Agonoderus  pallipes)  has  occasionally  done  consid- 
erable harm  by  devouring  the  seed  and  the  roots  of  the  young  plant. 

Several  small  species  of  the  family  Phalacridce,  and  others  of  the 
Nitidulidce,  similarly  infest  the  ear,  and  the  larva?  of  one  of  them,  Ips 


342  BULLETIN   No.  95.  [November, 

4-guttatus,  has  once  or  twice  been  known  to  eat  the  planted  seed.  Two 
or  three  of  the  small  dung-beetles  and  some  of  the  leaf-chafers  do  similar 
injuries  to  the  kernel  on  the  ear  or  in  the  ground.  A  number  of  the 
latter  group  occasionally  injure  the  young  plant  by  devouring  the  leaves 
or  eating  into  the  stalks.  Larvae  of  two  of  the  short-horned  borers 
(Prionus)  have  been  reported  as  rarely  injurious  to  the  roots  of  corn, 
and  a  considerable  number  of  the  plant-beetles,  flea-beetles,  and  the 
like  (Chrysomelidce) ,  are  variously  destructive  to  practically  all  parts  of 
the  plant. 

The  wireworms,  white  grubs,  and  bill-bugs  are  ah1  primarily  grass 
insects  (the  first  and  third  much  more  strictly  so,  however,  than  the 
second),  and  their  attacks,  consequently,  may  be  forestalled  wholly  or 
in  great  part  by  a  proper  management  of  the  land  with  respect  to  rotation, 
and  especially  by  using  care  in  changing  the  crop  from  grass  to  corn. 
The  corn  root-worm,  on  the  other  hand,  is  a  corn  insect  only,  and  its 
mischief  may  be  promptly  and  completely  arrested  in  any  case  arising, 
by  planting  corn  on  land  not  in  that  crop  the  preceding  year. 

Hemiptera:  True  Bugs. — Although  not  less  than  forty-five  recog- 
nized species  of  bugs  have  been  found  sucking  the  sap  from  some  part 
of  the  corn  plant  in  the  field,  to  say  nothing  of  several  others  which  have 
not  been  exactly  identified,  only  one  of  this  long  list  is  a  corn  pest  of  the 
first  class,  but  this  (the  chinch-bug)  is,  on  the  whole,  by  far  the  most 
destructive  insect  enemy  of  this  plant  in  America. 

The  false  chinch-bug  (Nysius  angustatus)  has  occasionally  injured 
corn  severely  in  our  territory,  making  its  way  into  the  field  from  infested 
wheat  adjoining,  and  the  tarnished  plant-bug  (Lygus  pratensis)  has 
rafely  been  found  responsible  for  noticeable  injury.  The  corn  root- 
aphis  (Aphis  maidi-radicis)  is  capable  of  killing  young  corn  by  sucking 
the  sap  from  its  roots,  but  more  frequently  it  merely  retards  the  growth 
of  the  plant  in  spring,  or  perhaps  permanently  dwarfs  it  by  this  early 
drain  on  its  vitality.  The  corn  leaf-aphis  (Aphis  maidis)  may  kill 
some  of  the  older  leaves  later  in  the  season,  but  although  it  often  con- 
tinues to  increase  in  numbers  until  frost  checks  its  multiplication,  it  can 
rarely  be  said  to  diminish  sensibly  the  amount  or  to  impair  the  quality 
of  the  crop.  Otherwise,  the  various  sucking  insects  which  are  found  on 
the  corn  plant  obtain  from  the  leaf,  the  stalk,  the  tassel,  the  silk,  the 
husk,  or  sometimes  from  the  soft  young  kernels  exposed  at  the  tip  of  the 
ear,  an  amount  of  liquid  food  too  small  to  affect  the  growth  of  so  vigorous 
a  plant. 

Special  preventive  measures  are  necessary  or  profitable,  as  a  rule, 
only  against  the  chinch-bug,  and  will  be  discussed  in  connection  with  that 
insect,  although  injuries  by  minor  species  may  be  reduced  by  clean 
culture,  by  the  destruction  of  winter  harborage  for  insects,  and  by  a  few 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  343 

other  general  measures  characteristic  of  intelligent  and  careful  agri- 
culture. 

Orthoptera:  Grasshoppers,  Locusts,  and  Crickets. — About  twenty-five 
species  of  Orthoptera  have  been  noticed  as  common  in  corn-fields,  the 
larger  number  and  the  only  destructive  species  belonging  to  the  so-called 
short-horned  grasshoppers  (Acridities) .  Like  very  many  other  insect 
visitants  to  the  corn-field,  these  Acrididce  are  normal  grass  insects,  and 
go  into  the  corn  in  numbers  sufficient  to  attract  attention  only  when 
their  usual  food  threatens  to  fail,  and  their  injuries  are  consequently 
confined  at  first  to  the  edges  of  fields  adjoining  pastures  and  meadows. 
The  great  migrating  grasshopper  of  the  Western  Plains  is,  of  course,  an 
exception  to  this  statement,  and  an  occasional  migrant  swarm  of  certain 
Illinois  species  imitates  with  some  success  the  practices  of  this  western 
insect,  settling  upon  a  field  like  a  flock  of  birds,  and  doing  a  general 
injury. 

The  ordinary  grasshopper  attack  on  corn  is  rarely  made  by  the  young, 
and  is  consequently  postponed,  as  a  rule,  until  late  summer  or  early  fall, 
when  the  corn  is  practically  full  grown  and  the  insects  are  able  to  fly. 
Where  the  injury  is  severe  the  leaves  are  eaten  away  to  the  tough  midrib, 
the  husks  are  gnawed  from  the  ear,  and  the  latter,  if  still  young,  is  itself 
devoured,  little  but  bare  stalks  remaining  about  the  edges  of  the  fields. 
Fourteen  species  of  short-horned  grasshoppers  are  on  our  list  of  those 
injuring  corn  in  this  way. 

The  long-horned  grasshoppers  (Locustidce) ,  including  the  meadow 
grasshoppers,  climbing  crickets,  and  the  like,  are  not  uncommon  in  corn- 
fields, but  they  are  only  slightly  injurious  to  that  plant.  One  of  them, 
Orchelimum  xulgare,  has  occasionally  been  seen  to  eat  the  leaves,  silk,  husks, 
and  grain,  and  many  other  species  sometimes  gnaw  away  a  few  kernels 
from  the  tip  of  the  ear.  Several  kinds  of  these  insects  frequently  lay 
their  eggs  in  the  slender  part  of  the  corn-stalk,  in  or  below  the  tassel  of 
the  ripened  plant,  but  their  food  consists  mainly  of  pollen,  fungi,  plant- 
lice,  etc.,  and  indicates  no  injury  to  corn. 

Two  of  the  common  crickets  (Gryllus  abbreviatus  and  Nemobius  fas- 
ciatus)  sometimes  injure  the  ripened  ear,  especially  where  there  are 
many  fallen  stalks  in  the  field,  by  creeping  in  beneath  the  husks  and 
gnawing  off  the  surfaces  of  the  kernels. 

The  only  possible  protection  to  corn  against  grasshoppers  is  the 
destruction  of  these  insects  before  they  leave  the  grass-lands  adjoining, 
or  when  they  first  enter  the  corn-field.  Once  generally  distributed  in  the 
fields,  practically  nothing  can  be  done  to  arrest  the  injury.  For  their 
destruction  in  pastures  and  meadows,  some  one  of  the  methods  must  be 
chosen  which  has  been  found  effective  against  these  insects  in  the  West. 
These  are,  generally  speaking,  the  plowing  in  fall  of  ground  heavily 
stocked  with  grasshoppers'  eggs,  or  plowing  even  in  summer  for  the 


344  BULLETIN  No.  95.  [November, 

destruction  of  the  young,  the  burning  over  of  grass-lands  after  the  young 
have  hatched,  the  collection  of  the  egg  masses  where  these  have  been 
abundantly  deposited,  poisoning  heavily  the  outer  rows  of  corn  with 
arsenic  or  Paris  green,  distributing  along  the  edges  of  the  field  quantities 
of  poisoned  horse-droppings,  the  so-called  Griddle  mixture,  and  catching 
the  insects  in  meadows  and  pastures  by  the  use  of  the  "hopper-dozer." 
The  most  important  of  these  procedures  will  be  more  fully  discussed  on 
another  page. 

Neuroptera:  Dragon-flies,  Lace-wings,  etc. — No  insect  injurious  to 
corn  belongs  to  the  order  Neuroptera,  which,  in  fact,  need  be  mentioned 
in  this  connection  only  to  say  that  the  occasional  abundance  in  corn- 
fields of  the  delicate  and  interesting  lace-wing  fly  (Chrysopa)  is  to  be 
connected  with  the  occurrence  of  plant-lice  there,  upon  which  both 
larval  and  adult  lace-wings  feed.  The  winged  insects  we  have  found  in 
corn-fields  eating  the  spores  of  fungi,  the  surface  hairs  of  the  leaf,  and 
other  delicate  vegetable  tissues. 

Acari:  Mites. — The  mites  commonly  known  as  the  red  spiders 
(Tetranychus  bimaculatus  and  T.  modestus)  have  been  rarely  found  inju- 
rious to  the  young  corn  leaf,  causing  a  rusty  or  brownish  discoloration. 
This  injury  to  corn  seems  to  have  been  too  rare,  however,  to  be  worthy 
of  special  attention,  although  the  wide-spread  distribution  and  destructive 
capacity  of  these  insects  suggest  the  possibility  that  they  may  be  respon- 
sible for  greater  injury  to  this  plant  than  has  been  attributed  to  them. 

Myriopoda. — Several  species  of  millipedes  and  centipedes  are  occa- 
sionally encountered  in  corn-fields  doing  a  slight  and  infrequent  injury 
only,  by  gnawing  into  the  kernels  beneath  the  husks.  They  are  most 
likely  to  injure  ears  which  touch  the  ground,  but  sometimes  climb  the 
stalk  as  much  as  two  or  three  feet. 

THE  CORN  INSECTS  GROUPED  ACCORDING  TO  THEIR  ECONOMIC 
IMPORTANCE. 

The  number  of  insects  infesting  corn  is  so  very  large,  and  the  propor- 
tion of  them  which  are  seriously  injurious  to  that  crop  is  comparatively 
so  small,  that  it  is  necessary,  for  practical  reasons,  to  separate  the  impor- 
tant insects  from  the  remainder  in  this  discussion.  I  have  consequently 
divided  the  entire  list  of  corn  insects  into  three  groups,  according  to 
their  economic  importance,  placing  in  the  first  group  of  "the  more  impor- 
tant corn  insects"  those  which  do  so  serious  an  injury  to  the  crop  that 
every  corn-grower  should  know  the  principal  facts  concerning  them  as 
an  essential  part  of  his  knowledge  of  farming;  in  the  second  group;  of 
"the  less  important"  insects,  those  which  are  sometimes  definitely  inju- 
rious but  ordinarily  do  no  great  harm ;  and  in  the  third  group,  of  "  unim- 
portant" insects,  those  which  do  little  or  no  injury  to  corn  as  a  farm  crop, 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  345 

and  which  may,  consequently,  be  practically  ignored  by  the  farmer  as 
insignificant. 

I  have  thought  it  best  that  the  first  group  should  be  made  as  small  as 
is  reasonable  and  safe,  and  have  placed  no  species  in  it  which  there  was 
not  positive  reason  to  consider  as  a  destructive  corn  pest.  The  second 
group,  on  the  other  hand,  I  have  made  to  include  all  of  the  other 
species  which  are  known  to  have  any  tangible  economic  significance 
whatever. 

The  first  group  may  be  said  to  contain  those  species  concerning 
which  every  practical  corn  farmer  should  know  the  essential  facts;  the 
second  group,  those  additional  species  which  should  be  familiarly  known 
to  the  economic  entomologist;  and  the  third  group,  those  which  are  of 
interest  chiefly  to  the  general  entomologist — the  student  of  entomological 
ecology — who  wishes  an  exhaustive  knowledge  of  the  entomology  of  the 
corn  plant. 

Notwithstanding  this  distinction,  it  should  be  remembered  that  nega- 
tive knowledge  is  sometimes  little  less  valuable  than  positive;  that  it 
may  sometimes  be  as  interesting,  and  even  as  important,  for  a  farmer  to 
know  that  a  species  appearing  for  the  first  time  in  his  fields  is  not  defi- 
nitely injurious  as  it  is  to  recognize  it  at  once  as  an  insect  enemy.  The 
more  he  can  learn,  consequently,  of  the  great  association  of  corn  insects 
treated  in  this  report,  the  better  prepared  he  will  be  to  handle  his  crop 
intelligently  under  all  conditions. 

It  must,  of  course,  be  admitted  that  the  dividing  lines  between  these 
groups  are  more  or  less  arbitrary,  and  at  best  but  poorly  defined,  the 
division  between  the  first  and  second  being  especially  hard  to  establish. 
An  insect  may  be  highly  important  to  corn  culture  at  some  times  and  in 
some  parts  of  the  country,  and  of  little  or  no  importance  elsewhere  and 
ordinarily,  and  differences  of  judgment  will  unavoidably  arise  as  to  the 
group  in  which  a  given  species  should  be  placed.  The  history  of  economic 
entomology  makes  it  also  virtually  sure  that  certain  species  now  prop- 
erly placed  in  one  of  the  less  important  groups  will  require  hereafter  to  be 
transferred  to  a  more  important  one,  and  the  group  division  here  pro- 
posed may,  on  this  account,  become  more  or  less  inaccurate  in  course  of 
time. 

The  reverse  proposition  is,  however,  much  less  likely  to  be  true.  It 
will  rarely  occur  that  a  species  once  recognized  as  seriously  destructive 
to  corn  will  drop  to  an  inferior  place  on  the  list.  It  sometimes  happens, 
indeed,  that  an  alien  insect  species  is  much  more  numerous  and  destruc- 
tive for  a  few  years  following  upon  its  first  appearance  in  the  country 
than  it  ever  is  again,  but,  as  a  matter  of  fact,  no  single  corn  insect 
of  any  considerable  importance  is  such  an  alien  species — has  come 
into  the  country,  that  is  to  say,  since  corn  became  an  important 
American  crop. 


346  BULLETIN   No.  95.  [November, 

It  is  possible,  also,  that  the  normal  progress  of  agriculture  may  make 
virtually  universal,  farming  practices  which  will  serve  as  permanent 
preventives  of  injury  by  certain  insects  which  have  previously  done  great 
harm.  If,  for  example,  it  should  become  the  general  rule  to  raise  corn 
on  the  same  ground  for  only  two  or  three  years  at  a  time,  injuries  by  the 
corn  root-worm  would  apparently  be.  reduced  to  insignificance.  No  such 
event  has  anywhere  occurred  in  this  country,  however,  and  the  rule  of 
economic  entomology  has  thus  far  been  "once  an  enemy  always  an 
enemy,"  the  list  of  insect  pests  increasing  from  time  to  time,  but  never 
diminishing, 

DISCUSSION  OF  SPECIES. 

In  the  remainder  of  this  report  I  give  all  pertinent  facts  of  any  impor- 
tance known  to  me  concerning  the  corn  insects  which  frequent  that  part 
of  the  plant  which  grows  above  the  surface  of  the  ground,  exclusive, 
however,  of  those  which  infest  the  grain  or  the  fodder  after  these  have 
been  removed  from  the  field.  In  order  to  make  this  treatise  virtually 
complete  for  the  corn  insects  as  a  group,  I  have  made  references,  at  the 
end,  to  a  previous  article  on  injuries  to  the  seeds  and  roots  of 
Indian  corn,  published  in  my  Seventh  Report  as  State  Entomologist — 
the  Eighteenth  of  the  office  series — and  also,  in  briefer  form,  in  Bulletin 
44  of  the  State  Agricultural  Experiment  Station.  The  above-mentioned 
Eighteenth  Report  may  be  found  in  volume  31  of  the  Transactions  of 
the  Illinois  State  Department  of  Agriculture,  where  it  is  printed  as  an 
appendix. 

ECONOMIC  GROUP  1. 

(The  more  important  insects:  those  seriously  injurious  to  the  crop,  either  as  locally 
and  occasionally  destructive  or  as  widely  and  frequently  harmful.) 


INSECTS  INJURIOUS  TO  THE  PLANT  ABOVE  GROUND. 
SYNOPSIS  OF  INJURIES. 

PAGE 

The  plant  cut  off  when  young  at  or  near  the  surface  of  the  ground  by 
a  whitish,  grayish,  or  blackish  caterpillar  frequently  found  in 

the  earth  near  the  injured  plant 

Cutworms  (Agrotis,  Hadena,  etc.).  347 

The  stalk  of  the  young  plant  eaten  into  or  irregularly  gnawed  off. 
The  leaves  also  irregularly  eaten.  A  small,  spotted  reddish  cater- 
pillar found  under  ground  near  the  base  of  the  plant  in  a  small 

mass  of  earth  held  together  by  a  web 

Sod  Web- worms  or  Root  Web-worms  (Crambus).  366 


1904.]  INSECT  INJURIES  TO   INDIAN   CORN.  347 

PAUK 

The  stalk  of  the  young  plant  penetrated  by  a  round  hole  which  is 
more  or  less  plugged  by  excrement.  The  interior  of  the  stalk 

irregularly  eaten  out  by  a  striped  burrowing  caterpillar 

The  Stalk-borer  (Papaipema  nitela).  374 

The  entire  plant  more  or  less  completely  eaten,  the  leaves  first  and 
then  the  stalk,  in  June  and  early  July,  by  hordes  of  traveling 
striped  caterpillars  commonly  coming  into  the  field  from  one 
side The  Army- worm  (Leucania  unipuncta).  377 

The  stalk  punctured  and  slit,  the  leaves  perforated  by  round  or  ob- 
long holes  arranged  in  parallel  transverse  rows.  Hard-shelled, 
oval,  black  or  clay-colored  snout-beetles  often  found,  head 
downward,  on  the  stalk  near  the  ground  or  a  little  beneath  the 
surface Corn  Bill-bugs  (Sphenophorus) .  382 

Plant  wilted  or  sickly,  leaf-edges  and  lower  leaves  turned  yellow  or 
brown,  many  small  red  or  dusky,  or  blackish  and  whitish  bugs 
behind  the  leaf  sheaths  of  the  corn,  or  clustered  on  outer  surface 
of  the  stalk The  Chinch-bug  (Blissus  leucopterus) .  387 

The  leaves  of  the  plant  variously  eaten,  sometimes  stripped  to  the 
midrib,  about  the  borders  of  the  field,  in  late  summer  or  fall. 

The  silks  and  husks  also  more  or  less  eaten  away 

Grasshoppers  (Acrididce).  394 

The  husk  of  the  ear  perforated  by  a  round  hole  with  the  excrement  ex- 
uding, the  corn  mined  beneath  by  a  brownish,  or  greenish,  striped 
caterpillar  . .  .  .The  Ear- worm  or  Corn-worm  (Heliqthis  armiger).  397 

THE  CORN  CUTWORMS. 

Hadena  devastatrix  Brace.  Nephelodes  minians  Guen. 

H.  arctica  Boisd.  Hadena  lignicolor  Guen. 

Agrotis  ypsilon  Rott.  Noctua  clandestina  Harr. 
Peridroma  margaritosa  saucia  Hiibn.       Feltia  annexa  Tr. 

Noctua  c-nigrum  Linn.  Euxoa  messoria  Harr. 

Feltia  subgothica  Haw.  E.  tesselata  Harr. 

F.  jaculifera  Guen.  E.  ochrogaster  Guen. 

F.  gladiaria  Morr.  Mamestra  renigera  Steph. 

The  caterpillars  commonly  known  as  "cutworms"  destroy  the  youn» 
corn  plant  by  eating  the  leaves,  gnawing  into  the  stalks,  and  cutting  off 
the  plant  close  to  the  ground  at  night,  often  dragging  the  severed  part 
into  their  holes  near  by.  They  hide  by  day  under  clods,  or  by  burying 
themselves  a  little  distance  in  the  earth,  where  they  may  be  easily  found 
curled  up  into  a  close  spiral  or  a  circular  disk.  They  are  thick,  soft- 
bodied,  rather  sluggish  caterpillars,  with  nearly  smooth  skins,  varying 
in  color  from  whitish  to  dark  brown,  variously  marked,  in  many  cases 
with  longitudinal  stripes,  and  often  with  dark  dashes  and  blotches  addi- 


348  BULLETIN  No.  95.  [November., 

tional.  They  are  most  destructive  in  corn  following  on  grass  or  clover, 
but  sometimes  come  into  the  field  from  meadow  or  pasture  lands  adjoin- 
ing, when  the  outer  rows  of  corn,  of  course,  suffer  worst.  Where  they 
are  very  numerous  it  is  virtually  impossible  to  obtain  a  stand  of  corn 
until  the  period  of  their  active  injuries  is  passed.  Many  of  them,  when 
they  become  so  numerous  on  any  spot  as  to  overtax  their  food  supply, 
move  out  of  the  overpopulated  field  in  companies  not  unlike  those  of  the 
notorious  army-worm.  The  latter  belongs,  indeed,  to  the  cutworm 
family,  and  when  only  ordinarily  common  lives  and  feeds,  generally 
speaking,  like  the  cutworms  of  this  list. 

Most  of  the  species  pass  the  winter  partly  grown,  and  are  consequently 
prepared  to  make  their  attack  on  corn  as  soon  as  it  shows  above  ground. 
They  enter  the  earth  for  their  transformations  when  full  grown,  at  times 
varying  for  the  different  species,  most  of  them  in  late  June  or  early 
July.  They  change  in  the  earth  to  leathery,  brown  pupae,  from  which 
grayish  or  brownish  night-flying  moths — the  adults  of  the  species- 
emerge  later  in  the  season,  and,  laying  their  eggs  in  grass-lands,  perish 
before  the  winter.  The  young  hatching  from  these  eggs  live  on  the  roots 
of  grasses  until  cold  weather,  doing  no  noticeable  injury,  as  a  rule,  during 
this  fall  period. 

The  greater  part  of  them  develop,  in  our  latitude,  only  a  single  gen- 
eration each  year,  but  a  few  of  the  most  destructive  species  are  two-  or 
three-brooded.  This  fact  seems  to  make  little  difference,  however,  from 
the  economic  point  of  view,  except  as  the  single-brooded  species  are  less 
able  than  the  others  to  take  prompt  advantage,  by  their  rate  of  increase, 
of  specially  favorable  conditions  of  location,  crop,  or  weather  of  the 
season. 

Injury  to  corn  by  cutworms  is  best  prevented  by  midsummer  or 
early  fall  plowing  of  grass-lands  to  be  planted  to  corn;  by  pasturing  pigs 
on  grass  or  clover  lands  to  be  plowed  up  for  corn;  by  distributing,  by 
the  aid  of  a  seed-drill,  a  line  of  dry  bran  or  middlings,  poisoned  by  mixing 
in  Paris  green  at  the  rate  of  a  pound  of  the  poison  to  thirty  pounds  of 
the  food-stuff,  or  by  scattering  poisoned  food  in  spring  along  the  borders 
of  corn-fields  next  to  grass;  and  by  replanting  when  corn  is  killed  by 
them,  postponing  this  step,  however,  until  the  cutworm  injury  has  prac- 
tically ceased  for  the  season.  The  earlier  the  preceding  year  grass-lands 
to  be  planted  to  corn  are  plowed,  the  less  will  be  the  probability  that  the 
cutworm  moths  will  have  laid  their  eggs  thereon,  and  the  less,  conse- 
quently, will  be  the  danger  of  injury  by  cutworms  the  following  year. 

The  points  in  the  life  history  of  the  various  cutworms  essential  to 
successful  management  are  thus  the  time  when  the  greater  part  of  the 
eggs  are  laid  for  the  hibernating  brood  of  the  caterpillars,  and  the  time 
when  this  hibernating  brood  gets  its  growth  in  spring,  ceases  its  injuries, 
and  goes  into  the  ground  for  its  change  to  the  pupa  state.  The  first 


1904.] 


INSECT  INJURIES  TO   INDIAN   CORN. 


349 


date  shows  when  the  ground  should  be  plowed  for  corn  in  fall;  and 
the  second,  when  it  may  safely  be  planted  or  replanted  to  corn  in 
spring. 

Cutworms  entering  the  corn-field  from  pastures  or  meadows  adjoin- 
ing, may  be  effectively  and  cheaply  poisoned  by  placing  along  the  edges 
of  the  field  fresh  clover  or  other  succulent  vegetation  which  has  been  cut 
after  spraying  thoroughly  with  Paris  green  stirred  up  in  water  at  the 
rate  of  a  pound  to  fifty  gallons. 

The  sixteen  species  whose  names  are  placed  at  the  head  of  this  sec- 
tion have  all  been  found  injuring  corn — only  the  first  nine  of  them,  how- 
ever, notably  harmful  to  that  crop  in  Illinois. 


THE  GLASSY  CUTWORM. 
Hadena  devastatrix  Brace. 

This  is  a  translucent,  whitish  caterpillar  (Fig.  1),  slightly  tinted  with 
bluish  green,  without  body  spots  or  blotches,  the  head  red  or  red-brown, 
and  the  neck-shield  brownish.  Its  appearance  has  been  quite  aptly 
characterized  as  midway  between  that  of  a  white  grub  and  a  common 
cutworm.  It  is  quite  similar  to  the  yellow-headed  cutworm  next 
described,  from  which  it  is  most  readily  distinguished  by  its  darker  head 
and  neck-shield,  and  the  lighter  color  of  its 
body. 

In  view  of  the  destructive  nature  of  its 
attacks,  its  wide-spread  range  and  great 
abundance,  and  the  numerous  published 
reports  of  serious  injury  to  crops,  this  cut- 
worm may  be  properly  regarded  as  the  most 
serious  pest  of  its  kind  to  corn  and  grass. 
It  is  rarely  seen  above  ground,  but  works 
mainly  in  a  burrow  beneath  the  surface, 
feeding  principally  at  night,  eating  off  the 
roots  close  to  the  base  of  the  stem,  or  cutting 
off  the  latter  under  ground. 

We  have  found  it  very  destructive  to 
corn  in  Peoria  and  Henry  counties,  and 
frequently  occurring  in  corn  hills  in  various 
parts  of  the  state.  A.  J.  Cook  reports  it  as 
injurious  to  corn  in  Michigan;  Lintner,  in 
New  York;  and  Harvey,  in  Maine.  Gillette 
pronounces  it  the  most  abundant  and  destructive  cutworm  in  .corn  and 
grass  in  Iowa;  Smith  reports  it  as  one  of  the  most  destructive  of  its  kind  in 
New  Jersey;  and  Fletcher  finds  it  injurious  in  Manitoba.  It  frequently 
becomes  so  numerous  in  meadows  as  to  be  notably  injurious  to  grass.  In 


FIG.  1.  The  Glassy  Cutworm 
(Hadena  devastatrix),  back  and 
side  views.  Enlarged. 


350  BULLETIN    No.  95.  [November, 

Ohio,  for  example,  twenty  acres  out  of  thirty  of  a  timothy  meadow  were 
so  injured  by  this  cutworm  that  the  grass  became  dry  enough  to  burn. 

In  mixed  fields  of  timothy  and  clover 
they  have  completely  destroyed  the 
timothy,  leaving  the  clover  unharmed. 
In  Indiana  a  large  area  in  each  of  three 
timothy  fields,  amounting  to  fifty  acres 
in  all,  was  totally  destroyed.  There  was 
FIG.  2.  The  Glassy  Cutworm  (Hadena  an  evident  migration  of  the  cutworms  in 

devastatrix) ,  adult.     Natural  size.  ,  .  r    ,,        ,  i        j      •  1-1 

this  case  out  of  the  low  lands  in  which 

they  originated.  They  have  destroyed  lawns  in  Fargo,  North  Dakota, 
and  in  Glencoe,  near  Chicago.  In  Canada  it  was  found  necessary  to 
plow  up  several  fields  of  winter  wheat  which  were  destroyed  by  them  in 
spring,  and  fields  of  oats  were  seriously  injured  and  replanted.  A  piece 
of  sod  land  in  Ohio  badly  infested  by  these  cutworms  was  broken  up  in 
winter  and  planted  to  seedling  peaches,  but  in  the  following  spring 
thirty-five  per  cent,  of  these  young  trees  were  cut  off  two  or  three  inches 
above  the  roots.  Lugger  says  that  they  are  very  destructive  to  straw- 
berry plants  in  Minnesota,  cutting  away  the  crown  and  causing  the  plant 
to  wilt  away.  They  have  also  injured  strawberry  plants  in  the  Southern 
States  and  garden  vegetables  in  Mississippi. 

Besides  these  farm  crops  they  may  feed  upon  almost  any  kind  of 
herbaceous  plants,  including  cabbages,  beans,  radishes,  hollyhocks,  and 
lettuce.  They  evidently  develop  mainly  in  grass-lands,  especially  in 
low  ground,  and  do  their  most  serious  injuries  to  crops  following  upon 
grass. 

The  species  is  found  in  the  United  States  from  the  Atlantic  to  the 
Pacific,  and  also  in  Canada  and  in  Europe.  It  is  least  abundant  in  the 
extreme  South. 

It  appears  to  be  single-brooded.  The  eggs  are  laid  in  the  latter  part 
of  the  season,  mostly,  according  to  Gillette,  after  August  1,  and  hatch 
before  cold  weather,  the  larva?  making  their  destructive  attack  in  the 
latitude  of  central  Illinois  in  the  following  May  and  the  first  half  of  June. 
They  change  to  the  pupa  in  the  ground  in  June  or  the  early  part  of  July, 
occasionally  as  late  as  August.  The  moths  (Fig.  2)  begin  to  appear  in 
June,  become  very  abundant  in  August,  and  may  remain  until  October. 
Garman  found,  November  25,  a  single  cutworm  of  this  species,  which 
reached  the  moth  stage  the  following  April. 

From  this  it  follows  that  grass-lands  must  be  plowed  in  August  if 
they  are  to  remain  free  from  the  eggs  of  this  cutworm  moth,  and  that 
corn  planted  late  in  June  will  probably  remain  uninjured  by  the  cut- 
worm itself. 


1904.]  INSKCT   IN.IUHIKS  TO    INDIAN    COKN.  351 

THE  YELLOW-HEADED  CUTWORM. 
Hadena  arctica  Boisd. 

It  is  very  similar  in  appearance  to  the  glassy  cutworm  just  described, 
but  may  be  distinguished  by  the  fact  that  its  body  is  pale  smoky  gray, 
while  the  head  and  neck-shield  are  both  tawny  yellow.  It  is  without 
stripes,  spots,  or  other  body  colors.  It  is  so  similar  to  the  preceding  spe- 
cies that  it  has  often  been  confused  with  it,  and  it  is  consequently  impos- 
sible to  separate  published  statements  concerning  injuries  due  to  the 
two.  It  lives  usually  about  two  inches  under  ground,  cutting  off  the 
roots  of  grasses,  grains,  and  corn,  and  the  stems  below  the  surface. 

It  is  frequent,  but  not  very  common,  in  Illinois,  and  is  widely  dis- 
tributed northward  in  Canada,  Labrador,  Vancouver,  and  in  subarctic 
America  and  Europe  generally.  It  occurs  as  far  south  as  New  Mexico, 
and  is  generally  wide-spread  east  of  the  Rocky  Mountains.  In  1895  the 
moths  were  so  abundant  in  western  Ontario  as  to  be  a  general  nuisance, 
filling  lamps  and  windows,  and  soiling  curtains  and  clothes.  In  the 
following  season  these  cutworms  did  great  damage  to  fields  of  oats, 
wheat,  and  corn,  many  of  the  fields  being  plowed  up  and  replanted. 
Cook  has  also  found  it  injurious  to  corn  in  Michigan.  In  New  York, 
Fitch  observed  that  these  cutworms  would  finish  first  any  living  grass 
remaining  in  the  corn-field,  but  would  then  attack  the  crop  itself. 

Besides  grasses  and  cereal  crops,  they  feed  on  various  herbaceous 
plants,  such  as  cabbage,  spinach,  and  lettuce,  and  on  succulent  shoots, 
like  those  of  roses  and  currants. 

This  cutworm  lives  longer  in  the  stage  of  destructive  activity  than 
many  of  the  other  species,  often  continuing  its  injuries  beyond  the 
middle  of  June,  and  even  into  July.  It  pupates  in  June  or  July,  and  the 
moths  begin  to  appear  late  in  June,  becoming  commonest  in  July  and 
early  August  and  lasting  until  September.  Eggs  have  been  deposited  as 
early  as  June  13. 

THE  GREASY  CUTWORM. 
Agrotis  ypsilon  Rott. 

This  is  a  common,  wide-spread,  and  destructive  cutworm,  injurious  to 
garden  vegetables  and  to  fruits  as  well  as  to  corn.  When  full  grown 
(Fig.  3)  it  is  about  an  inch  and  a  half  in  length,  of  an  almost  uni- 
form dark,  greasy  gray,  with  a  faint  dorsal  stripe  of  dull,  dirty  yellow. 
Beneath,  it  is  an  obscure  greenish  yellow. 

This  is  a  typical  cutworm  in  its  feeding  habits,  and  is  one  of  the 
commonest  of  its  kind  in  corn.  It  feeds  also  on  grass,  asparagus,  cot- 
ton, tobacco,  tomato,  cabbage,  potato,  spinach,  squash,  beans,  beets, 


352 


BULLETIN   No.  95. 


[November, 


apple,  grape,  and  strawberries,  but  has  not  been  reported  as  injurious 
to  clover  or  as  breeding  in  fields  of  that  crop. 

It  is  found  throughout  the  United  States, 
and,  indeed,  throughout  the  world,  ranging 
to  the  northward  as  far  as  Manitoba  and 
Hudson  Bay,  to  the  south  as  far  as  Uru- 
guay and  New  Zealand,  and  the  Cape  of 
Good  Hope  in  Africa.  It  occurs  in  India, 
Ceylon,  and  China,  and  is  a  common  Euro- 
pean species  also. 

While  destructively  abundant  at  times 
and  in  especially  favorable  situations,  it  is 
not,  so  far  as  we  know,  subject  to  periods  of 
very  extraordinary  increase.  It  is  much 
parasitized,  when  abundant,  by  dipterous 
and  hymenopterous  parasites,  and  these 
must  serve  as  a  severe  and  ready  check  upon 
its  multiplication. 

This  cutworm  is  apparently,  but  not 
certainly,  single-brooded.  It  passes  the  win- 
ter mainly  as  a  caterpillar,  in  various  stages 
of  growth ;  begins  to  feed,  of  course,  as  soon 
as  spring  revives  it,  and  continues  more  or 

less>  injurious  well  through  June,  and  sometimes  even  into  July.  The 
destructive  activity  of  this  cutworm  usually  reaches  its  height  in  the 
latter  half  of  May  and  in  early  June,  and  then  declines  gradually 
through  the  first  half  of  July.  A 
few  of  the  larvae  cease  feeding, 
however,  in  May,  and  complete 
their  changes  to  the  adult  stage 
(Fig.  4)  during  that  month,  but 
the  transformations  of  the  greater 
part  of  the  hibernating  generation 
occur  in  June.  Egg-laying  be- 
gins, according  to  our  observa- 
tions, in  July,  the  new  generation  sometimes  beginning  to  hatch  in 
the  grass  within  a  fortnight  of  the  disappearance  of  the  last  of  the  cut- 
worms of  the  preceding  year.  This  species  may  consequently  be  found 
in  the  cutworm  stage  at  practically  all  times  and  seasons.  Pupae  found 
in  our  breeding-cages  on  the  8th  of  June  gave  the  moths  in  four  weeks, 
and  eggs  laid  July  3  hatched  in  twenty-two  days. 

Beginning  early  in  July,  the  laying  of  eggs  doubtless  continues 
through  August,  and  possibly  into  September  also.  The  moths  have 
been  most  frequently  found  by  us  in  July  and  August,  with  only  occa- 


FIG.  3.  The  Greasy  Cutworm 
(Agrotis  vpsilon),  back  and  side 
views.  Enlarged. 


FIG.  4.    The  Greasy  Cutworm  (A  gratis  ypsilon) , 
adult.    Natural  size. 


1904." 


INSECT  INJURIES  TO  INDIAN   CORN. 


353 


sional  occurrences  in  September,   the  latest  on  our  notes  for  central 
Illinois  being  September  20. 

Breeding  almost  wholly  in  grass-lands,  its  injuries  to  corn  are  to  be 
apprehended  only  where  this  crop  follows  upon  grass,  or  where  the  corn- 
field adjoins  a  pasture  or  meadow.  In  the  former  case  the  injury  may 
be  generally  distributed  throughout  the  field,  but  in  the  latter  it  will  be 
limited  chiefly  to  the  side  next  to  grass.  It  continues  its  injuries  so 
late  in  spring  that  it  is  difficult  for  the  corn-grower  to  escape  it  by  late 
planting,  and  even  the  first  replanting  of  injured  fields  may  fall  a  sacrifice 
to  it;  but  plantings  made  as  late  as  the  first  or  second  week  in  June  will 
be  practically  safe  from  serious  injury  by  it.  On  the  other  hand,  the 
early  date  at  which  the  moth  begins  to  lay  her  eggs  lessens  the  value  of 
fall  plowing  as  a  preventive  measure.  Probably  pasturing  of  infested 
fields  of  grass  by  pigs  in  fall,  before  breaking  up  for  corn,  is  the  best  gen- 
eral preventive  measure  available  in  ordinary  practice. 


THE  VARIEGATED  CUTWORM. 
Peridroma  margaritosa  sauda  Hiibn. 
(Agrotis  saucia.} 

This  cutworm,  when  fully  grown,  is  about  an  inch  and  three-quarters 
long,  and  is  easily  recognized  by  its  conspicuous  markings.  (Fig.  5,  6,  c,  d, 
Fig.  6.)  The  general  effect  of  its  ground-color  is  grayish  or  brownish — 
usually  variable,  however,  being  light  or  dark  as  its  surroundings  expose 
it  more  or  less  to 
the  light,  those  on 
trees  or  bushes  be- 
ing darker  than 
those  feeding  near 
the  ground  o  n 
br  oad-leaved 
herbs.  It  is  most 
easily  distinguish- 
ed, when  of  aver- 
age color,  by  a 
row  of  four  to  six 
pale  dots  extend- 
ing from  the  neck 
half  way  or  more 
down  the  back, 

and  a  Velvety  Spot  FlQ    5      The  Variegated  Cutworm  (Peridroma  margarUosa  saucia) : 

rm       +Vio      corrmon-f        o,  adult;    b,  c,  d,  larvse ;  e,  f,  eggs.     Figure  e  greatly  enlarged;   others 
natural  size.    (Howard,  U.  S.  Dept.  of  Agriculture.) 

next  to  the  last, 

sharply  defined  behind,  but  shading  gradually  forward  into  the  dark 


354 


BULLETIN    No.  95. 


[November, 


ground-color  of  the  back.     The  freshly  hatched  caterpillars  are  greenish, 
with  black  heads. 

This  is  a  very  common  species,  but  is  peculiar  in  its  habits.  It  climbs 
plants  freely  at  night  to  feed,  even  ascending  bushes  and  fruit-trees,  and 

devouring  any  succulent  tissue  which  it 
finds,  including  bud,  fruit,  flower,  leaf,  stalk, 
or  root  of  the  plant.  It  occurs  frequently  in 
corn-fields,  although  not  ordinarily  common 
there.  When  very  abundant  it  sometimes 
migrates  in  hordes  like  the  army-worm,  in 
search  of  food,  and  under  such  circumstances 
has  been  known  to  destroy  hundreds  of 
acres  of  young  corn  in  a  comparatively  short 
time.  It  is  pre-eminently  a  garden  pest, 
however,  being  particularly  destructive  to 
fruits,  vegetables,  and  flowers  rather  than 
to  grain  crops,  weeds,  and  wild  plants.  A 
remarkable  outbreak  of  this  cutworm  oc- 
curred in  the  year  1900  in  the  United  States 
and  Canada,  especially  in  the  states  of  the 
Pacific  coast.  Enormous  damage  was  done 
by  it,  particularly  to  fruit  and  vegetable 
crops.  A  full  account  of  this  occurrence 
will  be  found  in  Bulletin  29,  N.  S.,  U.  S. 
Division  of  Entomology,  and  in  Bulletin  47 
of  the  Experiment  Station  of  Washington 
state.  Among  its  leading  food  plants  are 
cabbage,  tomatoes,  potatoes,  clover,  onions,  peas,  beets,  and  carnations. 
It  occurs  throughout  nearly  the  whole  of  the  New  World,  and  also 
in  western  and  southern  Europe,  northern  Africa,  and  Asia  Minor. 

Thje  seasonal  history  of  this  species  is  not  yet  well  understood.  It 
has  been  seen  in  winter  as  larva,  as  pupa,  and  as  adult,  and  entomolo- 
gists differ,  consequently,  in  their  statements  as  to  its  normal  hibernating 
stage  and  the  number  of  its  broods.  It  agrees  with  most  of  the  species, 
however,  in  the  fact  that  it  is  destructively  active  in  early  spring,  becom- 
ing most  injurious  in  May  and  early  June,  pupating  in  June,  and  begin- 
ning to  produce  moths  (Fig.  5,  a)  abundantly  in  the  latter  part  of  that 
month.  The  data  which  we  have,  suggest  at  least  two  broods  in  a  year, 
but  there  is  nothing  conclusive  upon  that  point.  Eggs  (Fig.  5,  e,  /)  of 
this  species  were  sent  to  us  March  27  on  an  apple  twig  from  Vandalia, 
and  others  were  sent  us  April  17  from  Hardin  county,  in  southern 
Illinois,  which  were  just  hatching  when  received.  The  young  cutworms 
were  kept  on  clover  until  May  26,  by  which  time  they  had  reached  an 
average  length  of  about  one  inch,  being,  in  other  words,  at  this  date  some- 


FIG.  6.  The  Variegated  Cut- 
worm (Peridroma  margaritosa 
saucia),  back  and  side  views.  En- 
larged. 


1904. 


INSECT  INJURIES  TO  INDIAN   CORN. 


355 


what  more  than  half  grown.  Female  moths,  on  the  other  hand,  confined 
in  a  breeding-cage  with  blue-grass  July  10,  had  given  origin  six  days 
later  to  freshly  hatched  larvae,  with  which  the  cage  was  swarming  at  the 
time.  Unfortunately,  these  presently  died — probably  because  the  food 
plant  offered  them  was  unsuitable.  Other  entomologists  have  several 
times  secured  and  hatched  the  eggs  of  this  species  in  the  latter  half  of  the 
season.  In  1900,  cutworms  of  this  species — probably  of  the  second 
brood — began  to  appear  early  in  July,  reached  their  greatest  abundance 
about  July  25,  and  had  disappeared  by  the  end  of  the  following  month. 
The  advent  of  winter  commonly  finds  individuals  in  every  stage  of 
growth,  and  moths,  larvae,  and  doubtless  pupae  also  may  pass  the  winter 
successfully.  We  once  found  four  larvae  in  early  December  under  boards 
and  weeds  in  grass  and  corn.  Two  of  these  were  about  a  third  of  an  inch 
in  length,  and  the  others  were  approximately  an  inch  and  a  quarter. 
Two  full-grown  larvae  were  also  found  January  14  and  24. 

Fortunately,  this  cutworm  is  not  ordinarily  sufficiently  injurious  in 
corn-fields  to  require  special  precautions  except  when  it  moves  in  com- 
panies from  its  breeding  grounds,  and  then  it  may  be  dealt  with  like  the 
army-worm,  by  measures  to  be  described  in  the  article  on  that  species. 

THE  SPOTTED  CUTWORM. 
Noctua  c-nigrum  Linn. 

The  spotted  cutworm  is  a  common  species,  injurious  in  Europe  as 
well  as  in  America,  especially  to  garden  vege- 
tables, which  it  seems  to  prefer  to  grasses  and 
grains.  It  has  occasionally  injured  Indian 
corn  in  various  states,  and,  like  the  species  just 
discussed,  is  liable  to  travel  in  companies 
when  it  becomes  very  numerous.  Under 
these  circumstances  it  might  require  the 
especial  attention  of  the  corn-grower.  It  is 
on  record  also  as  injuring  wheat  in  January 
and  in  March.  (Webster.) 

It  may  be  recognized  (Fig.  7)  by  two 
rows  of  triangular  black  spots,  one  on  each 
side  of  the  back,  with  the  narrow  angle  to  the 
front,  largest  and  darkest  on  the  posterior  seg- 
ments of  the  body,  and  fading  out  before  they 
reach  the  head.  The  general  color  of  the  cater- 
pillar is  pale  brownish  or  ashy  gray,  and  it  is 
about  an  inch  and  a  half  long  when  of  full  size.  FlG  7  The  Spotte(1  Cutworin 

It  hibernates  as  a  cutworm  nearly  full      v^^E^in?^'  hack  aml  s'He 
grown,  and  pupates  quite  early,  in  central  Illi- 
nois late  in  April  and  early  in  May;  consequently,  if  injuries  to  corn  are  due 


356 


BULLETIN  No.  95. 


[November, 


FIG.  8.    The  Spotted  Cutworm  (Nodua 
onigrum) ,  adult      Natural  size. 


to  this  species  they  will  soon  cease,  and  the  first  replanting  will  commonly 
escape  unharmed.  Moths  (Fig.  8)  from  pupae  formed  in  April  and  early 
May  have  appeared  in  our  breeding  experiments  during  the  latter  part 
of  May  and  the  first  half  of  June,  and,  proceeding  without  much  delay 
to  deposit  their  eggs,  they  gave  origin  to  a  second  brood  of  cutworms 
which  became  fairly  well  grown  about  the  middle  of  July.  This  genera- 
tion is  not  often  found  in  the  corn-field,  and  does  no  injury  there  worth 

noticing.  The  moths  from  this  sec- 
ond brood  have  appeared  in  our  breed- 
ing-cages from  late  July  to  the  middle 
of  August.  They  continue  alive  in 
the  fields  throughout  September,  and 
lay  their  eggs  in  grass  for  the  hiber- 
nating brood  of  the  cutworms. 

Early  fall  plowing  of  infested 
grass-lands  may  thus  be  expected  to  take  effect  on  this  cutworm  by  pre- 
venting the  laying  of  many  of  the  eggs,  and  by  causing  the  starvation  of 
many  of  the  young  which  may  already  have  hatched. 

THE  DINGY  CUTWORM. 
Feltia  subgothica  Haw. 

THE  WESTERN  STRIPED  CUTWORM. 

Feltia  jaculifera  Guen. 
(Agrotis  tricosa,  A.  herilis.) 

The  dingy  and  the  striped  cutworms  are  remarkably  alike  in  both 
appearance  and  habits,  and  may  well  be  treated 
together.  The  former  (Fig.  9)  is  dingy  gray, 
and  easily  recognized  by  the  dusky  band  on 
each  side  of  the  back,  obliquely  notched  on  the 
inner  border  like  the  edge  of  a  serrated  leaf. 
The  broad  dorsal  space  between  these  bands  is  a 
buff  y  gray.  There  are  also  a  well-marked  light 
band  along  each  side  of  the  body,  and  dorsal 
and  lateral  pale  lines  rather  feebly  marked. 

The  western  striped  cutworm  is  very  closely 
similar  to  the  preceding,  perhaps  indistin- 
guishable in  the  caterpillar  stage.  Riley  says, 
indeed,  that  it  is  more  dingy  than  sub- 
gothica, with  less  conspicuous  lines,  and  with 
a  more  decided  buff  tint  to  the  dorsal  band. 
These  differences  are,  however,  within  the 
range  of  ordinary  variation,  and  the  species 
can  apparently  be  distinguished  with  cer- 


FIG  9    The  Dingy  Cutworm 
**"*  and  "^ 


1904.]  INSECT  INJUKIES  TO  INDIAN   CORN.  357 

tainty  only  by  breeding  to  the  adult.     The  young  larvae  are  much  darker 
at  first,  sometimes  nearly  black. 

The  dingy  cutworm  is  one  of  the  commonest  species,  especially  in 
corn,  where  it  shares  with  the  greasy  cutworm  the  principal  injury  to 
that  crop.  Indeed,  there  is  some  reason  to  believe  that  the  moth  may 
lay  her  eggs  in  fall  among  the  succulent  weeds  in  the  corn-field,  particu- 
larly when  a  severe  drouth  has  made  the  pasture  and  meadow  lands  less 
inviting.  In  accordance  with  this  supposition  these  cutworms  have  not 
infrequently  been  found  in  early  spring  generally  distributed  through 
corn  on  old  corn  ground.  Stedman  speaks  of  it  in  Missouri  as  the  most 
destructive  cutworm  in  wheat.  In  our  breeding-cages  it  has  evidently 
preferred  clover  to  blue-grass.  It  is  especially  fond  of  early  vegetables, 
including  melons,  cabbage,  tomatoes,  beans,  peas,  sweet  potatoes,  tur- 
nips, lettuce,  celery,  and  strawberry  plants.  It  occasionally  climbs  fruit- 
trees  and  shrubs  to  devour  their  buds  and  leaves. 

The  striped  cutworm  is  also  decidedly  destructive  to  corn,  according 
to  Webster,  one  field  in  Indiana  being  completely  ruined  by  it  in  1895. 
Similar  injuries  were  noticed  in  the  same  year  in  Missouri,  Kentucky, 
Tennessee,  and  southern  Ohio.  It  was  the  most  abundant  cutworm  in 
southern  Illinois  in  the  outbreak  of  1887,  and,  next  to  gladiaria,  the  com- 
monest and  most  destructive  throughout  the  state  during  that  of  1888. 
It  did  much  harm  to  corn  in  these  years,  but  was  especially  injurious  to 
clover,  for  which  it  had  an  evident  preference,  and  to  the  meadow- 
grasses.  It  frequently  migrates  when  abundant  in  search  of  food,  but 
without  the  concerted  movement  of  the  true  army-worm. 

Both  of  these  species  are  generally  distributed  throughout  the 
United  States  and  Canada  east  of  the  Rocky  Mountains.  The  dingy 
cutworm  is  also  found  on  the  Pacific  coast,  and  we  have  specimens  of 
the  moth  from  Montana,  Wyoming,  and  Utah.  The  striped  species 
occurs  in  British  Columbia. 

There  is  but  one  brood  of  the  dingy  cutworm  each  year.  Moths  have 
been  taken  throughout  July,  August,  and  September,  but  much  the 
most  abundantly  in  the  latter  part  of  August.  Eggs  are  quickly  depos- 
ited, and  hatch  in  about  a  week.  The  caterpillars  grow  slowly,  and 
hibernate  when  quite  small.  Those  taken  by  us  in  January,  February, 
and  March  averaged  less  than  half  an  inch  in  length,  but  when  warm 
weather  comes  they  grow  apace,  and  in  May  become  nearly  full  grown. 
In  June  they  cease  feeding,  mostly  in  the  first  half  of  the  month,  and 
enter  the  ground  for  pupation.  A  dingy  cutworm  kept  under  observa- 
tion in  my  insectary  from  May  15,  entered  the  ground  June  16,  and 
continued  as  a  larva  in  its  earthen  cell  until  August.  On  the  12th  of 
this  month  it  was  found  to  have  changed  to  the  pupa,  and  on  the  28th 
it  became  an  adult.  This  long-delayed  pupation  was  not  due  to  drouth, 
as  the  earth  in  the  breeding-cage  was  kept  moist,  and  even  wet.  Besides 


358 


BULLETIN    No.  95. 


[  November. 


the  above  we  have  found  larvae  of  different  lots  in  a  similar  condition  in 
our  breeding-cages  June  15,  July  2,  19,  and  23,  and  August  3.  These 
facts  indicate  an  unusually  long  period  of  midsummer  preparation  for 
the  pupal  transformation. 

This  life  history  suggests  nothing  exceptional  by  way  of  prevention 
or  remedy.  Where  the  field  has  become  infested  in  fall,  as  shown  by  the 
general  distribution  of  the  cutworms  in  the  corn  in  early  spring,  replant- 
ing, to  be  safe,  should  be  postponed  until  towards  the  middle  of  June. 

THE  CLAY-BACKED  CUTWORM. 

Feltia  gladiaria  Morr. 
This  cutworm  (Fig.  10)  is  usually  dark  in  average  color,  varying, 

however,  from  greenish  gray  to  dark  brown.  The  back  is  commonly 
decidedly  light,  grayish  white  or  straw  color,  or  occa- 
sionally reddish  brown.  This  light  dorsal  space  is  divided 
lengthwise  by  a  more  or  less  conspicuous  median  white 
line,  which  is  usually  bordered  with  darker.  On  each 
side  of  the  pale  dorsal  space  are  two  irregular  whitish 
lines.  The  full-grown  larva  is  about  an  inch  and  a 
quarter  in  length. 

This  species  is  extremely  variable  in  numbers,  multi- 
plying under  some  conditions  to  become  a  notable  and 
widely  destructive  pest,  and  then  occurring  in  scarcely 
noticeable  numbers  for  some  years  thereafter.  It  was 
not  distinguished  as  a  cutworm  until  1888,  when  it  was 
bred  to  the  adult  in  our  insectary.  In  1887  and  1888  it 
was  the  most  destructive  cutworm  in  Illinois,  especially 
to  clover  and  young  corn.  In  1895  it  was  by  far  the 
leading  species  in  a  general  cutworm  outbreak  in  Ken- 
tucky, and  caused  serious  injury  to  a  thirty-acre  field  of 
young  corn  on  old  sod  ground  near  Champaign.  In  1901 
it  was  one  of  the  most  abundant  cutworms  in  corn-fields 
in  western  Illinois,  and  was  excessively  abundant  in 

pansy  beds  at  Urbana,  cutting  off  and  destroying  all  the  plants.    During 

its  years  of   greatest  abun- 
dance here  it  was  especially 

notorious  for  its  injuries  to 

clover,  which  it  preferred  to 

blue-grass.      It   likewise   ate 

oats,  grass,  and  corn,  invading 

corn-fields      from      adjacent 

meadows,  and  devouring  the 

plants  as  it  went  as  thorough- 

Fio    11     The    Clay-backed  Cutworm  (FeUia  giddi- 
ly as  does   the  army- worm.     aria)_  aduit.   Enlarged. 


Fio.  10.  The 
Clay-backed  Cut- 
worm  (Feltia 
gladiaria).  En- 
larged. 


1904.1  INSECT   INJURIKS  TO   INDIAN    CORN.  359 

It  fed  likewise  on  potatoes,  beans,  sweet  potatoes,  cabbage,  tomatoes, 
and  onions.  When  very  abundant  and  their  food  supply  had  run  short, 
these  cutworms  scattered  in  all  directions — a  habit  common  in  varying 
degrees  to  most  of  the  cutworms.  Its  mode  of  feeding  is  different  from 
that  of  the  cutworms  generally,  the  corn  leaf  being  seized  by  the  hang- 
ing tip,  drawn  down,  and  eaten  to  the  base.  In  clover  fields,  it  begins 
at  the  tip  of  the  plant  and  works  downward,  collecting  about  the  roots. 

This  species  is  registered  as  inhabiting  the  United  States  east  of  the 
Rocky  Mountains,  but  we  have  specimens  of  the  adult  from  Utah  and 
Colorado  also. 

It  spends  the  winter,  in  our  latitude,  in  the  caterpillar  stage,  and  is 
active  in  the  destruction  of  its  food  plants  from  the  middle  of  April  to 
the  beginning  of  June.  By  the  middle  of  June  all  the  cutworms  have 
entered  the  earth  for  transformation.  They  do  not  change  forthwith  to 
the  pupa  stage,  but  remain  there  for  a  considerable  period — more  than 
six  weeks  in  some  cases — in  a  dormant  or  torpid  condition.  Moths 
(Fig.  11)  consequently  do  not  appear  until  September  and  early  October, 
being  most  numerous  in  the  latter  half  of  September.  Eggs  are  then 
laid  without  delay,  and  from  these  the  larvae  hatch,  which  pass  the  winter 
partly  grown. 

It  follows  from  this  life  history  that  the  main  measure  for  the  protec- 
tion of  corn  against  this  cutworm  must  be  an  impassable  furrow  along 
the  margin  of  the  field  next  to  grass  or  clover,  or,  in  the  absence  of 
this,  the  distribution  of  poisoned  food — clover  particularly — where  the 
cutworms  are  likely  to  be  drawn  to  it.  Owing  to  the  lateness  of  the 
period  when  the  eggs  are  laid,  a  reasonably  early  fall  plowing  will  pre- 
vent the  breeding  of  the  species  on  that  ground. 

THE  BRONZE  CUTWORM. 
Nephelodes  minians  Guen. 

This  is  an  unusually  large  and  plump  cutworm  (Fig.  12)  about  an 
inch  and  three-quarters  in  length,  conspicuously  marked  with  alternate 
stripes  of  olive-bronze  and  yellowish,  the  former  much  the  broader.  A 
pale  stripe  runs  along  the  middle  of  the  back,  and  there  are  two  such 
on  each  side,  the  lower  below  the  spiracles.  The  bronze  space  imme- 
diately above  the  last  is  frequently  divided  lengthwise  by  a  delicate, 
broken  yellow  line.  The  head  is  yellowish  or  gray,  the  neck-shield 
darker,  with  five  pale  stripes. 

This  is  essentially  a  grass  cutworm,  being  one  of  the  commonest  of 
its  kind  in  grass-lands  in  early  spring.  It  is  somewhat  injurious  to  corn, 
especially  if  this  is  planted  on  pasture  or  meadow-lands  occupied  by  it 
the  preceding  year.  It  eats  clover  sparingly  or  not  at  all,  "but  seems  to 
have  a  special  preference  for  timothy.  In  the  corn-field  it  devours  the 


360 


BULLETIN  No.  95. 


[November. 


whole  plant  instead  of  merely  gnawing  through  the  stem.  It  is  not  a 
garden  species,  although  it  sometimes  climbs  fruit-trees  when  its  normal 
food  is  scarce,  feeding  on  the  buds  and  leaves  like 
other  so-called  climbing  cutworms. 

It  is  generally  common  and  abundant  through- 
out the  United  States  and  Canada.  In  Iowa  it 
is  regarded  by  Gillette  as  the  most  abundant 
species,  next  to  the  glassy  cutworm,  in  fields  of 
grass  and  corn.  It  did  much  injury  to  grass  in 
New  York  in  1881,  and  worked  unprecedented 
destruction  in  1886  near  Columbus,  Ohio,  where, 
late  in  May,  scarcely  an  acre  of  meadow  or  pas- 
ture had  a  vestige  of  grass  on  it  for  a  distance  of 
several  miles,  many  fields  being  dry  enough  to 
burn.  About  three  thousand  acres  were  thus 
destroyed,  the  larvae  migrating  en  masse  when 
their  food  was  exhausted. 

Hibernating  in  our  latitude  in  the  larval  stage, 
they  are  found  active  in  grass-lands  in  April  and 
throughout  May.  They  begin  to  disappear  about 
the  1st  of  June,  and  all  are  gone  by  about  the 
middle  of  that  month .  They  remain  under  ground 
for  a  considerable  period  without  pupating, 
changing  in  late  July  and  August.  The  moths  (Fig.  13)  first  appear  in 
early  August,  become  most  abundant  during  the  first  half  of  September, 
and  continue  into  October.  The  hibernating  caterpillars  have  the  singu- 
lar habit  of  sometimes  coming  forth  in  winter  and  crawling  about  on  the 
snow  and  ice.  In  the  South,  adults 
are  frequently  taken  during  the  win- 
ter months. 

This  cutworm  is  present  in  very 
unequal  numbers  year  after  year, 
what  seems  to  be  a  bacterial  disease 
checking  its  increase  when  it  becomes 

11  ••          i  ,->.          .,  .  Fio.  13.    The  Bronze  Cutworm  (Nephelodes 

Unusually     abundant.       On     thlS     aC-    miniang),  adult.    Natural  size. 

count,  and  also  because  much  subject 

to  insect  parasitism,  it  is  not  likely  to  be  excessively  abundant  in  the 

same  locality  for  two  successive  years. 

The  facts  concerning  it  suggest  no  special  preventive  or  remedial 
measures  other  than  those  frequentlyref erred  to  in  this  article.  Where 
it  is  so  abundant  in  grass-lands  as  to  threaten  a  migratory  movement, 
this  may  be  arrested  by  measures  usually  applied  against  the  army- 
worm.  In  case  it  scatters  into  corn  from  adjacent  fields  of  grass,  it  may 
doubtless  be  killed  by  the  use  of  poisoned  food,  particularly^the  mixture 


FIG.  12.  The  Bronze  Cut- 
worm (Nephelodes  minians), 
back  and  side  views.  En- 
larged. 


1004. 


INSECT  INJURIES  TO   INDIAN   CORN. 


361 


of  middlings  and  Paris  green.  In  case  corn  is  so  injured  by  it  as  to 
require  replanting,  this  may  be  safely  done  any  time  after  the  first  of 
June,  or  possibly  as  early  as  the  last  week  in  May.  To  be  sure  that  a 
grass  sod  shall  be  virtually  free  from  the  eggs,  this  should  be  plowed  as 
early  as  the  first  week  in  September. 

HADENA  LIGNICOLOR  GUEN. 

This  cutworm  closely  resembles  the  glassy  cutworm,  but  has  never 
been  fully  described  in  the  caterpillar  stage.  We  have  not  found  it  com- 
mon in  Illinois,  but  have  collected  the  moths  during  June,  July,  and 
August.  '  Gillette  reports  that  the  moths  are  very  common  in  Iowa. 
They  are  found  generally  in  the  northern  part  of  the  United  States  east 
of  the  Rocky  Mountains,  and  have  been  reported  from  Arizona. 

A  cutworm  of  this  species  which  was  found  by  Lintner  preparing  for 
pupation  May  18,  completed  its  transformations  and  came  out  as  a 
moth  on  the  29th  of  June.  Females  dissected  by  Gillette  July  13, 
were  well  filled  with  eggs. 

These  facts  indicate  a  comparatively  early  close  of  active  life  as  a 
cutworm,  and  a  comparatively  early  appearance  of  the  adult  moth. 

THE  W-MARKED  CUTWORM. 
Noctua  clandestina  Harr. 

This  caterpillar  (Fig.  14)  is  marked  with  four  longitudinal  rows  of  dark 
spots  and  some  dark  and  pale  longitudinal  lines.     The  spots  of  the  outer 
row  on  each  side  are  oblique,  and  sometimes 
unite  to  form  a  continuous  line;  those  on  the 
inner  row  are  more  or  less  triangular  (most 
evidently  so  on  the  hinder  segments),  and  occa- 
sionally have  the  shape  of  the  letter  W. 

This  is  a  very  wide-spread  species  and  a 
general  feeder,  but  is  ordinarily  much  more 
abundant  in  the  East  than  in  the  north-central 
states.  It  is  not  found  in  the  South.  Dr.  Lint- 
ner regards  it  as  the  most  injurious  corn  cut- 
worm in  New  York,  where  it  is  said  to  be  com- 
mon also  on  grass  and  grain,  and  to  feed  on 
buckwheat  and  clover.  It  is  fond  of  garden 
vegetables,  and  feeds  on  lettuce,  cabbage,  celery, 
pumpkins,  and  beans.  It  is  a  well-known  climb- 
ing cutworm,  ascending  trees  and  shrubs  to  eat 
the  buds  and  leaves,  particularly  those  of  the 
apple,  box-elder,  soft  maple,  currant,  and 
gooseberry.  Plantain  is  mentioned  as  one  of  its 
wild  food-plants. 


FIG.   14.      The    W-marked 

Cutworm  (Noctua  clandestina) , 
back  and  side  views.  Enlarged. 


362 


BULLETIN    No.  95. 


[November. 


The  larvae  winter  over  about  half  grown,  arid  mature  early,  becoming 
most  injurious  in  April  and  May.  The  moths  begin  to  appear  soon  there- 
after, and  are  most  abundant  about  June  20.  The  data  on  record 
indicate  a  probable  second  brood  of  the  cutworms  in  midsummer,  the 
moths  appearing  in  August,  September,  and  October. 

The  early  transformation  of  the  hibernating  brood  renders  precau- 
tions against  this  cutworm  virtually  unnecessary,  since  it  can  injure  only 
very  early  plantings  of  corn. 

THE  GRANULATED  CUTWORM. 
Feltia  annexa  Tr. 

This  species  is  best  known  "by  its  rough,  granulated  skin,  and  by  a 
pair  of  oblique  marks  on  each  segment,  diverging  backward.  (Fig. 
15,  a,  e.) 

It  is  a  general  feeder,  devouring  corn,  wheat,  and  other  cereals,  cotton, 
clover,  grass,  cabbage,  peas,  beans,  and  several  weeds.     It  is  particularly 
well  known  in  the  Southern 
States  as  a  cotton  cutworm, 
sometimes  so  b'adly  injuring 
this   crop   as   to   compel    re- 
planting. 

It  is  not  common  in  Illi- 
nois, but  is  found,  neverthe- 
less, across  the  country  from 
Massachusetts  to  California, 
and  is  abundant  from  Ken- 
tucky southward,  and  also  in 
Cuba  and  South  America. 
Lugger  records  a  single  cap- 
ture in  Minnesota. 

The  facts  with  regard  to  its  seasonal  history  have  not  yet  been 
clearly  established.  It  seems  to  winter  as  a  larva,  and  is  most  destructive 
in  April  and  May.  Moths  (Fig.  15,  h)  of  this  brood  appear  in  June,  July, 
and  August.  From  eggs  laid  August  3,  moths  were  reared  again  by 
October.  Beutenmuller  says  a  second  brood  flies  in  August,  September, 
and  October.  There  are  almost  certainly  two  generations  in  a  year  in 
Illinois,  and  quite  likely  three,  or  more,  in  the  Gulf  States. 

THE  DARK-SIDED  CUTWORM. 

Euxoa  messoria  Harr. 

The  common  name  of  this  cutworm  (Fig.  16,  a)  is  due  to  the  contrast 
of  a  dark  stripe  on  each  side  with  the  ashy  gray  ground-color.  The 
small  shining  spots  surrounding  the  hairs  are  conspicuous  and  black. 


FIG.  15.  The  Granulated  Cutworm  (Feltia  annexa); 
a,  larva;  6,  its  head,  front  view;  c,  d,  one  segment,  top 
and  side  view;  e,  surface;  /,  pupa;  g,  tip  of  pupa;  h, 
adult.  Figures  a,  /,  h,  natural  size,  others  enlarged. 
(Howard,  U.  S.  Dept.  of  Agriculture. 


1904. 


INSECT   INJURIES  TO    INDIAN    CORN. 


363 


FIG.  16.  The  Dark-sided  Cutworm 
(Euxoa  messaria) ,  la-va  and  adult.  Nat- 
ural size. 


Although  one  of  the  great  destruc- 
tive cutworms  of  the  United  States, 
this  species  is  not  reported  as  particu- 
larly injurious  to  corn.  It  is  one  of  the 
climbing  cutworms,  and  its  most  noto- 
rious injuries  are  done  to  fruits  and 
garden  vegetables.  It  is  charged  with 
a  great  destruction  of  the  peach  crop 
in  Illinois,  Indiana,  and  Michigan  in 
1887,  and  with  devouring  about  half 
the  onion  crop  of  Orange,  N.  J.,  in 
1885  and  1887,  and  again  in  1896.  In 
California  it  was  held  responsible  in 
large  part  for  the  defoliation  of  grape- 
vines in  Fresno  county.  Smith  speaks  of  it  as  the  most  injurious  cut- 
worm in  southern  New  Jersey,  especially  to  sweet  potatoes.  It  ascends 
fruit-trees,  the  apple  especially,  and  eats  the  buds  of  both  flowers  and 
leaves.  It  feeds,  besides,  on  cabbage,  spinach,  lettuce,  potatoes,  toma- 
toes, beans,  peas,  radishes,  turnips,  tobacco,  and  sugar-beets.  Specimens 
in  confinement  have  freely  eaten  grass,  corn,  clover,  buckwheat,  cur- 
rant, soft  maple  leaves,  and  various  fleshy  weeds.  Indeed,  it  is  so  gen- 
eral a  feeder,  Gillette  remarks,  that  in  confinement  it  has  not  refused  to 
eat  any  green  thing  offered  it. 

This  species  is  not  particularly  common  in  Illinois,  and  has  been 
rather  infrequent  in  our  collections  either  as  caterpillar  or  as  moth.  It 
has  been  reported  injurious,  however,  from  New  York  to  California  and 
Washington  state,  and  northward  into  Canada.  It  seems  to  be  com- 
paratively rare  to  the  southward. 

It  is  evidently  a  single-brooded  species,  the  caterpillars  being  most 
abundant  in  May  and  disappearing  by  the  middle  of  June.  Occasionally 
adults  (Fig.  16,  6)  occur  in  the  latter  part  of  June,  but  the  main  body  of 
them  appear  late  in  July,  and  are  most  abundant  in  September  up  to 
about  the  20th.  The  stage  of  hibernation  is  not  yet  positively  ascer- 
tained. Caterpillars,  apparently  of  this  species,  were  taken  by  me  from 
the  stomachs  of  robins  shot  in  February  and  March,  and  the  species 
probably  hibernates  in  the  larval  stage. 

Highly  satisfactory  experiments  for  the  destruction  of  this  species 
and  the  protection  of  garden  crops  have  been  made  by  Sirrine,  in  New 
York,  who  used  a  mixture  of  twenty  or  thirty  pounds  of  middlings  or 
bran — the  former  preferred — to  one  of  Paris  green.  A  continuous  row 
of  this  poisoned  bait  was  laid  along  the  ground  by  means  of  a  seed-drill. 


364  BULLETIN   No.  95.  [November, 

THE  COMMON  STRIPED  CUTWORM. 

Euxoa  tessellata  Harr. 

About  one  and  a  fourth  inches  in  length,  gray  in  general  color,  with 
a  pale  central  dorsal  line  and  three  pale  lines  each  side,  the  lower  one  the 
broadest. 

The  recorded  food  plants  of  this  cutworm  are  corn,  potato,  onion, 
tobacco,  radish,  squash,  cabbage,  lettuce,  tomato,  celery,  spinach,  beans, 
flax,  cucumber,  melon,  beet,  and  parsnip,  together  with  smartweed, 
Rumex,  and  various  weeds,  plum,  apple,  pear,  and  cherry.  In  confine- 
ment it  feeds  freely  upon  grass,  clover,  buckwheat,  box-elder,  and  the 
fleshy  weeds.  It  is  not  on  record  as  especially  injurious  to  corn,  being 
evidently  a  garden  species  rather,  and  my  own  observations  support  this 
statement.  Cook  found  it  injuring  corn  in  Michigan,  and  Fitch  in  New 
York,  the  latter  treating  it  in  his  Ninth  Report  under  the  name  of  the 
corn  cutworm. 

It  is  essentially  a  northern  species,  very  abundant  in  the  northern 
United  States  and  Canada,  but  less  common  in  central  Illinois  and  south- 
ward. The  caterpillar  hides  in  the  earth  by  day, 
cuts  off  the  plants  by  night  about  half  an  inch 
above  ground  (and  not  below  the  surface,  as  do 
the  Hadenas),  and  drags  the  leaves  into  its  hole 
to  feed  upon  them  during  the  day. 

There  is  but  one  brood  a  year,  and  the  cut- 

Fio.    17.      The    Common 

striped    Cutworm    (Euxoa     WOrms  pass  the  winter  about  half-grown,  becom- 

tessellata) ,  adult. 

ing  most  destructive  in  the  latter  part  of  May 

and  the  first  of  June.  The  moths  (Fig.  17)  are  most  abundant  early  in 
July.  They  have  been  taken  in  Iowa  from  early  June  to  the  beginning  of 
August,  and  in  Canada  during  the  latter  half  of  July  and  all  of  the  follow- 
ing month. 

THE  RED-BACKED  CUTWORM. 
Euxoa  ochrogaster  Guen. 

This  is  a  very  well-marked  species,  the  caterpillar  quite  large,  more 
than  an  inch  and  a  half  long,  gray  or  dull  brown,  with  a  broad  sienna-red 
stripe  down  the  middle  of  the  back. 

It  is  a  Canada  cutworm  especially,  ranging  from  Prince  Edward 
Island  to  British  Columbia,  and  often  excessively  abundant  in  that  lati- 
tude. It  is  less  abundant  in  the  northern  United  States,  and  is  not 
reported  from  localities  farther  south  than  Missouri,  Colorado,  and 
California. 

It  is  regarded  by  Fletcher  as  the  worst  corn  pest  among  the  Canadian 
cutworms.  It  is  also  particularly  troublesome  in  gardens,  attacking  all 
garden  vegetables  and  flowering  annuals.  It  has  not  been  found  by  us 


1904.] 


INSECT  INJURIES  TO  INDIAN   CORN. 


365 


in  corn  in  Illinois,  and  is,  so  far  as  our  observations  go,  scarcely  to  be 
regarded  as  an  economic  species  in  this  state. 

The  larvae  are  present  in  the  field  through  May  and  June,  and  some- 
times into  the  following  month.  The  moths  occur  in  the  latter  part  of 
June  and  in  July  and  August,  with  scattering  examples  continuing  into 
October.  There  is  apparently  but  one  brood  a  year. 

THE  BRISTLY  CUTWORM. 
Mamestra  renigera  Steph. 

This  is  a  small  yellowish  gray  species  (Fig.  18)  about  an  inch  in 
average  length  when  full  grown,  marked  by  two  blackish  stripes,  one  on 
each  side,  with  an  unusually  broad  pale  dorsal  area  between  them. 
There  are  other  less  conspicuous  stripes  and 
lines,  and  the  hairs  are  coarse  and  long,  giv- 
ing the  caterpillar  a  bristly  appearance. 

This  abundant  little  cutworm  has  been 
occasionally  found  by  us  at  the  base  of  in- 
jured corn  plants,  but  it  is  mainly  a  grass 
and  garden  species,  the  spring  brood  of  the 
caterpillars  getting  their  growth  too  early  to 
injure  corn  materially.  It  feeds  mainly  on 
the  roots  of  its  food  plants,  especially  on  gar- 
den flowers.  The  food  plants  listed  are 
clover,  the  common  grasses,  chicory,  tur- 
nips, and  comfrey,  to  which  we  add  corn 
and  cabbage.  Gillette  reared  specimens 
on  cotton  wood  leaves  and  alfalfa. 

This  species  is  found  from  Canada  to 
Georgia,  Colorado,  and  New  Mexico,  and 
it  has  been  reported  as  very  abundant  in 
Iowa,  Illinois,  Ohio,  and  New  York. 

There  are  two  generations  each  year, 
one  of  which  hibernates  as  a  cutworm  par- 
tially grown.     We  have  taken  young  larvae  at  frequent  intervals  from 
December  2  to  April.     Injury  to  crops  by  this  species  is  most  serious 

in  central  Illinois  in  the  latter  part  of  April 
and  early  in  May.  The  cutworms  pupate 
during  May,  and  the  moths  (Fig.  19)  appear 
in  the  latter  part  of  that  month,  continu- 
ing common  until  the  middle  of  July. 
Representatives  of  the  second  brood  of  cut- 
worms have  been  found  in  early  August, 
and  the  second  brood  of  moths  begins  to  appear  late  in  that  month,  and 
continues  through  September  and  into  early  October.  In  Kentucky  the 


FIG.  18.  The  Bristly  Cutworm 
(Mamestra  renigera),  back  and  side 
views.  Enlarged. 


FIG.  19.  The  Bristly  Cutworm 
(Mamcstra  renigera),  adult.  En- 
larged. 


366 


BULLETIN   No.- 95. 


[November, 


first  generation  of  the  moths  was  reported  present  from  April  until  after 
the  middle  of  June,  and  the  second  generation  in  August  and  September. 
In  Iowa  the  moths  are  said  to  be  most  abundant  in  June,  and  again 
about  the  end  of  August.  In  Canada  the  first  generation  begins  to  ap- 
pear late  in  June. 


THE  SOD  WEB-WORMS,  OR  ROOT  WEB-WORMS. 
SEVERAL  SPECIES  OF  CRAMBUS. 

Every  observer  of  insect  life  has  noticed,  as  he  walks  through  grass  on 
lawns  or  meadows  in  summer,  multitudes  of  small  white  or  grayish  moths 
(Fig.  21,  23)  rising  before  him,  flying  a  short  distance,  and  then  lighting 
to  rest  on  the  grass,  head  downward,  with  the  body  parallel  to  the  blade. 
These  moths,  or  millers,  if  examined  when  at  rest,  are  seen  to  have  the  wings 
folded  around  the  body  in  a  way  to  give  them  a  cylindrical  form  instead  of 
the  usual  triangular  one  of  ordinary  moths.  These  are  the  parent  insects  of 
small,  slightly  bristly,  reddish  caterpillars  which  live  abundantly  in  the  turf, 
hidden  away  by  day  in  a  silk-lined  burrow  among  the  roots  of  the  grass,  but 
becoming  active  at  night,  when  they  feed  especially  upon  the  underground 
part  of  the  stem  of  the  plant,  sometimes  also  upon  its  roots  or  blades. 

General  Description. — These  caterpillars  (Fig. 
20,  22)  average  about  half  an  inch  in  length  when 
full  grown,  are  pinkish  red  or  brownish,  and  cov- 
ered with  rows  of  comparatively  smooth  dark 
spots,  from  the  center  of  each  of  which  springs 
a  rather  coarse  hair.  They  differ  from  cutworms 
in  their  habit  of  quickly  wriggling  away  when 
picked  up  or  disturbed,  and  making  active  efforts 
to  escape.  Cutworms,  on  the  other  hand,  are 
sluggish,  and  take  disturbance  quietly,  simply 
curling  up  and  taking  their  chances. 

Injuries. — Not  infrequently  the  web-worms 
become  so  abundant  as  to  cause  brown  or  dead- 
ened spots  in  a  lawn  or  meadow,  sometimes, 
indeed,  in  seasons  unfavorable  to  the  growth  of 
grass,  deadening  the  turf  as  thoroughly  as  white 
grubs  or  cutworms  can  do.  When  land  so  in- 
fested is  planted  to  corn,  this  plant  is  very  likely 
to  be  heavily  injured,  or  even  completely  de- 
stroyed over  considerable  areas  in  early  spring. 
The  injury  done  is  somewhat  like  that  due  to 
cutworms,  and  is  largely  under  ground,  but,  on 

the  other  hand,  the  stems  are  rarely  completely  severed  until  the  whole 
plant  is  eaten  up.     Commonly  the  first  injury  to  the  plant  is  done  by 


FIG.  20.  The  Sod  Web- 
worm  (Crambus) :  web  (a) 
containing  larva,  at  base  of 
young  corn  plant;  6,  c,  in- 
juries to  leaf  and  stem 


1904.J  INSECT   INJURIES  TO   INDIAN    CORN.  367 

gnawing  the  outer  surface  beneath  the  ground  and  about  the  roots. 
Then  the  caterpillar  works  upward,  eating  a  superficial  furrow  or  bur- 
rowing lengthwise  along  the  center  of  the  stem.  The  leaves  are  also 
frequently  eaten,  the  lower  ones  first,  and  then  the  upper  ones.  The 
tips  are  eaten  off,  or  irregular  elongate  holes  are  eaten  through  the 
blades.  The  injury  being  done  at  night,  search  must  be  made  for  the 
author  of  it  by  day  by  digging  around  the  affected  hills.  The  web-worms 
will  commonly  be  found  just  below  the  surface  (Fig.  20,  p.  371),  each  in 
a  retreat  formed  by  loosely  webbing  together  a  mass  of  dirt,  more  or 
less  cylindrical  in  shape,  an  inch  and  a  half  to  two  inches  long,  and 
about  half  an  inch  through.  Within  this  mass  is  a  silk-lined  tube  open- 
ing at  the  surface  of  the  ground  next  to  a  stalk  of  corn,  and  within  this 
specially  prepared  domicile  a  single  caterpillar  is  secreted.  Injuries 
due  to  these  web-worms  are  commonly  attributed  by  farmers  to  cut- 
worms, and  the  caterpillars  themselves  are  similarly  confounded.  This 
error  would  signify  but  little  except  for  a  single  important  difference 
in  the  midsummer  life  history  which  has  its  bearing  on  the  proper 
time  of  plowing  the  sod  in  spring,  and  that  for  planting  or  replanting 
the  corn.  Cutworms  are  never  protected  by  an  underground  web,  are 
much  larger  than  web-worms,  make  no  active  efforts  to  escape  when 
disturbed,  but  curl  up  and  remain  inactive,  and  are  without  rows  of 
conspicuous  shining  spots  upon  the  body,  these  being  represented  by 
small  and  inconspicuous  ones. 

The  injury  to  corn  by  the  sod  web-worms  is  not  uncommon  in  fields 
planted  on  sod  ground,  and  as  it  begins  quite  early  and  may  last  some 
weeks,  it  is  fully  as  serious  as  a  similar  attack  by  cutworms  or  white 
grubs.  Frequently  more  or  less  extensive  replanting  is  required,  and 
sometimes  whole  fields  are  completely  destroyed  two  or  three  times  in 
succession.  In  Ohio,  for  example,  hundreds  of  acres  of  corn  and  oats 
were  as  completely  killed  in  1895  as  if  burned  over,  and  similar  injuries 
to  corn  have  been  reported  from  New  York,  New  Jersey,  Delaware, 
Maryland,  Illinois,  Iowa,  and  Nebraska.  In  Illinois  and  Iowa  it 
was  a  most  serious  corn  pest  in  1887,  destroying  corn  on  sod  ground 
in  many  fields  distributed  through  several  counties  in  both  these 
states;  and  in  Pennsylvania  it  was  found  destructive  to  corn  in  1891, 
most  injurious  here  as  elsewhere,  in  one  case  at  least,  on  old  timothy  sod. 
Besides  its  occasional  injuries  to  corn,  and  to  small  grain  where  this 
follows  upon  grass — a  rare  event,  indeed,  at  least  in  Illinois — its  principal 
injuries  are  to  grass  in  meadows  and  pastures.  Its  injuries  here  are 
much  greater  than  are  commonly  attributed  to  it.  "This  fact  is  due," 
says  Dr.  Felt,  "to  its  very  insidious  methods  of  work." 

"  Unless  the  damage  they  do  is  very  serious  it  is  hardly  noticed,  or, 
if  noticed,  attributed  to  other  causes.  As  the  larvae  live  a  retired  life, 
close  to  the  surface,  eating  mostly  at  night  and'  remaining  in  their  nests 


368  BULLETIN  No.  95.  [November, 

during  the  day,  they  are  rarely  seen.  Like  most  larvae  they  feed  most 
voraciously  just  as  they  are  completing  their  growth;  consequently, 
when  the  damage  is  noticed  most  of  the  larvae  are  hidden  in  their  retreats 
where  they  pupate.  In  these  places  none  but  an  experienced  entomolo- 
gist would  find  them,  or  would  think  of  associating  the  damage  done 
with  the  harmless  appearing  moths  that  fly  later. 

"Hardly  any  farmer  would  think  seriously  of  the  loss  of  only  one 
stalk  of  grass  in  ten,  yet  the  aggregate  for  the  country  at  large  would 
be  enormous.  Not  only  is  the  damage  to  a  crop  where  nothing  short  of  a 
serious  injury  would  attract  attention,  but  the  damage  is  distributed 
throughout  the  growing  season.  As  a  general  rule,  each  species  is  most 
destructive  at  a  different  time  from  the  other  species  of  that  locality; 
hence,  species  of  Crambus  prey  upon  the  grass  as  a  succession  of  small 
armies.  Could  the  loss  caused  by  these  species  come  at  one  time  in  the 
year  their  destructive  power  would  be  better  appreciated.  Less  than  a 
third  of  the  species  may  be  classed  as  of  economic  importance,  but  these 
possess  a  capacity  to  cause  almost  infinite  loss  if  the  conditions  are 
favorable." 

Additional  Examples  of  Injury.  From  Office  Notes. — At  Champaign, 
May  28,  1885,  Crambus  larvae  were  injuring  young  corn  by  gnawing  the 
outer  leaves  at  the  surface  of  the  ground,  and  also  by  eating  out  irregular 
holes  in  the  leaves  and  the  blades  themselves.  Frequently  the  leaves 
were  eaten  off  and  lying  on  the  ground  or  partly  drawn  into  the  mouth 
of  the  web.  Occasionally  a  plant  was  gnawed  completely  through  at 
the  surface  of  the  ground,  as  by  a  cutworm.  The  injury  here  was  suffi- 
cient to  cause  a  partial  replanting  of  the  field.  This  land  had  been  in 
pasture  for  fifteen  years,  and  no  damage  to  the  grass  had  been  noticed. 
It  was  plowed  about  the  8th  or  9th  of  May,  and  planting  was  finished 
May  15. 

At  Milan,  in  Rock  Island  county,  August  13,  1885,  farmers  reported 
the  presence  of  a  worm  which  made  a  web  at  the  roots  of  the  corn  and 
ate  the  leaves  while  young,  after  which  it  worked  about  the  roots, 
cutting  them  off  just  below  the  surface  of  the  ground.  Seven  acres  of 
corn  on  sod  were  almost  completely  destroyed,  only  a  hill  here  and  there 
being  left.  These  larvae  fed  mostly  in  the  evening  and  just  after  a 
shower.  They  had  been  seen  traveling  from  one  hill  of  corn  to  another. 

At  Mt.  Pulaski,  Logan  county,  Illinois,  according  to  observations 
and  statements  made  June  16,  1885,  larvae  of  Crambus  zeellus  (=  lutco- 
lellus)  had  so  far  injured  a  small  field  of  eight  acres  of  corn  that  it  had 
been  replanted  about  the  last  day  of  May.  On  the  16th  of  June  the 
worms  were  still  somewhat  active,  and  corn  plants  were  frequently 
seen  which  had  been  more  or  less  injured  by  it.  Many  of  the  webs  were 
vacant,  however,  the  larvae  evidently  having  gone  largely  into  the  earth 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  369 

for  pupation.    This  field  had  never  been  plowed  until  the  preceding  fall, 
when  it  was  broken  up  for  corn. 

A  field  of  corn  near  Philo,  in  Champaign  county,  Illinois,  visited 
June  1,  1886,  was  found  unevenly  infested  by  this  insect,  one  patch  of 
about  an  acre  being  completely  destroyed.  This  corn  was  on  sod  broken 
April  7  and  planted  May  7  and  8. 

July  31,  1888,  blue-grass  was  found  entirely  killed  over  large  patches 
in  a  lawn  at  Urbana,  111.,  by  the  larvae  of  C.  trisectus,  and  numerous 
webs,  some  of  which  still  contained  the  larvae,  were  exposed  by  clearing 
away  the  dead  grass  on  the  lawns.  On  one  of  these  lawns,  which  ten 
days  before  had  been  thick  and  as  soft  as  velvet,  only  a  few  small  spots 
of  green  remained.  It  was  spotted  with  tufts  of  dead  grass  pulled  out 
by  the  birds,  many  species  of  which  were  evidently  feeding  freely  on 
the  web-worms.  The  larvae,  all  nearly  or  quite  full  grown,  were  trans- 
forming rapidly  at  the  date  of  this  observation. 

June  13,  1891,  caterpillars  of  trisectus  and  mutabilis  were  found 
seriously  injurious  to  forty  acres  of  corn  belonging  to  Mr.  W.  C.  Baker, 
near  Savoy,  Champaign  county,  Illinois.  At  least  two-thirds  of  the 
first  planting  of  the  forty-acre  field  had  been  destroyed,  and  much  of 
the  second  planting  also.  This  field  had  been  in  pasture  for  eight  or  nine 
years,  and  was  plowed  the  preceding  fall,  at  just  what  time  my  infor- 
mation does  not  indicate. 

Another  field,  of  eighty  acres,  adjoining  the  foregoing,  also  broken 
in  fall,  had  suffered  still  more  heavily,  most  of  the  first  two  plantings  of 
corn  being  devoured,  and  about  a  third  of  the  third  planting  also.  The 
caterpillars  were  still  somewhat  active  June  13,  but  most  of  them  had 
ceased  their  feeding  and  deserted  their  webs.  It  is  evident,  consequently, 
that  in  this  case  the  proper  time  for  replanting  would  have  been  about 
June  10,  and  that  corn  planted  at  this  time  would  have  escaped  serious 
injury. 

In  another  field  adjoining  this,  about  a  fifth  of  the  corn  had  been 
destroyed  on  sod  ground  plowed  in  spring.  This  field  had  also  been  in 
pasture  for  several  years. 

At  Knoxville  and  Oneida,  in  Knox  county,  Illinois,  corn  on  sod  ground 
examined  May  25,  1901,  was  found  damaged  by  the  larvae  of  trisectus 
and  vulgivagellus,  associated  with  ordinary  cutworms,  to  the  amount  of 
twenty-five  per  cent.;  and  at  Buda,  in  Bureau  county,  May  28,  a  field 
was  visited,  from  fifty  to  seventy-five  per  cent,  of  which  had  been  de- 
stroyed by  the  same  web-worms  and  striped  gophers,  necessitating  a 
second  planting. 

From  Office  Correspondence. — The  following  reports  of  injuries  by  the 
web- worms  are  from  my  office  correspondence.  All  were  verified  by  an 
examination  of  specimens. 


370  BULLETIN    No.  95.  {November. 

Galena,  Jo  Daviess  County,  111.,  May  23,  1887.  I  send  a  box  containing  worms 
which  are  very  destructive  to  corn  planted  on  spring-breaking.  [This  was  Crambus 
luteolellus.] 

Hoopeston,  Vermilion  County,  111.,  August  2,  1888.  About  three  weeks  ago 
noticed  that  the  blue-grass  on  my  lawn  was  beginning  to  die  in  spots.  Watering 
did  no  good.  On  examination  I  found  worms,  like  those  sent  you  to-day  by  mail, 
averaging  one  or  more  to  the  square  inch.  They  cut  off  the  blue-grass  at  the  top 
of  the  ground,  but  do  not  disturb  the  timothy  or  white  clover. 

Payson,  Adams  County,  111.,  May  21,  1886.  I  find  a  few  of  the  corn  root  web- 
worms  on  a  piece  of  clover  sod  plowed  this  spring  and  planted  April  30  and 
May  1.  I  find  them  as  often  on  clover  growing  in  the  field  as  in  the  hills  of  corn, 
and  I  think  they  may  breed  in  the  clover.  The  field  was  planted  to  corn  in  1881 
and  1882,  sowed  to  wheat  in  the  fall  of  that  year  and  again  the  year  following, 
sowed  to  clover  in  March,  1885,  this  being  plowed  up  in  the  spring  of  1886  and 
planted  to  corn. 

Smithfield,  Fulton  County,  111.,  May  31,  1887.  I  mail  specimens  of  a  worm 
that  is  cutting  the  corn  planted  on  sod.  They  are  likely  to  take  the  third  planting, 
and  are  working  some  on  stubble.  [This  was  Crambus  Irisectus.] 

Galesburg,  Knox  County,  111.,  May  2,  1887.  I  send  you  a  few  grubs  that  have 
been  eating  up  the  sod  corn.  I  find  them  on  meadow  plowed  up  last  fall,  also  on 
meadow  plowed  this  spring.  They  ate  up  nearly  every  hill  of  sod  corn,  but  did  not 
touch  corn  on  old  ground  next  to  it.  I  replanted  ten  days  ago.  The  new  planting 
is  now  big  enough  to  plow,  and  is  all  right  as  yet.  [These  larvae  belonged  to 
C.  trisectus  and  C.  mutabilis.] 

May  25.  I  learn  that  the  corn  on  a  large  scope  of  country  is  injured  in  the 
same  way  as  mine.  One  man  is  planting  his  sod  corn  to-day  for  the  third  time. 

Eden,  Peoria  County,  111.,  May  19,  1887.  I  send  by  this  mail  a  box  of  worms 
found  in  a  corn-field  on  our  farm.  The  field  was  an  old  timothy  meadow  plowed 
this  spring  and  planted  about  the  5th  of  May.  They  are  taking  the  corn  here  very 
rapidly. 

Randolph,  McLean  County,  111.,  May  16,  1887.  I  send  you  a  sample  of  worms 
destroying  our  corn.  The  land  is  timothy  sod  broken  the  first  two  weeks  in  April, 
and  planted  the  first  of  May.  It  has  been  in  meadow  for  five  years.  On  a  part  of 
it  considerable  clover  is  growing  from  seed  sown  two  years  ago,  and  on  this  part  the 
worms  are  not  so  bad.  The  rest  of  the  corn  is  taken  clean,  eaten  off  just  above  the 
ground.  We  find  the  worms  an  inch  deep  in  the  ground,  the  dirt  being  stuck 
together.  Some  of  them  are  very  small;  others  are  half  an  inch  long.  [C.  tri- 
sectus and  C.  mutabilis.] 

Hanover,  Jo  Daviess  County,  111.,  May  24,  1887.  1  inclose  several  specimens 
of  worms  which  have  done  a  great  deal  of  damage  to  corn  in  this  county  this  spring. 
The  damage  has  been  exclusively  on  sod  ground,  both  fall  and  spring  plowing 
suffering  alike.  From  reports  from  different  parts  of  this  county  I  learn  that  the 
ravages  of  this  worm  are  general  throughout  the  county.  The  plant  is  attacked 
just  at  the  surface  of  the  ground,  where  the  worm  weaves  a  web  to  protect  itself 
from  ants  and  other  enemies,  and  then  the  stalk  is  eaten  downward.  One  piece  of 
ten  acres  on  rich  black  soil  on  my  own  farm  I  replanted  entire  on  the  14th  of  May, 
and  now  the  worms  bid  fair  to  destroy  it  entirely  again.  Hundreds  of  acres  have 
been  replanted  in  my  own  town,  and  the  area  of  ground  in  the  county  damaged  by 
this  worm  will  reach  into  the  thousand  acres.  [C.  luteolellus.] 

Hamlet,  Mercer  County,  111.,  May  19,  1887.  My  corn  is  infested  with  a  larva 
that  is  a  stranger  to  me.  This  morning  I  collected  a  few  of  them,  and  put  them  in 
a  box  directed  to  you.  They  do  their  work  at  night  above  ground,  and  mostly  on 
the  upper  part  of  the  leaves,  but  often  cut  the  stalk  off  at  the  base  of  the  leaves. 


1904. 


INSECT  INJURIES  TO  INDIAN   CORN. 


371 


Their  nest  has  its  mouth  close  to  the  corn  they  are  eating,  but  may  run  on  the 
ground  an  inch  before  going  down.  It  consists  of  a  web  case,  to  which  the  dirt 
adheres.  They  are  doing  their  worst  work  on  a  piece  of  ground  on  which  rye  was 
grown  last  year.  I  often  find  two  or  three  of  them  to  a  single  hill  of  corn.  They  are 
mostly  small,  but  I  have  found  a  few  over  an  inch  in  length. 

Glenwood,  Cook  County,  111.,  June  15,  1888.  I  send  you  inclosed  some  cots 
which  are  supposed  to  belong  to  the  web-worm.  I  broke  up  and  planted  to  corn 
seventeen  acres  of  timothy  sod  that  had  been  seeded  about  twelve  years,  and  I  find 
these  cots  lying  around  on  this  ground.  The  cutworms  are  so  plenty  that  they  do 
not  let  the  corn  get  much  above  ground. 


FIG.  20.  The  Common  Sod  Web-worm 
(Crambus  trisectus) ,  back  and  side  views. 
Much  enlarged. 


FIG.  22.  The 
Striped  Sod  Web- 
worm  (Crambus 
mutabilis).  Much  en- 
larged . 


FIG.  21.  The  Common  Sod  Web-worm 
(Crambus  trisectus),  adult.  Slightly  en- 
larged. 


FIG.  23.    The  Striped  Sod  Web-worm  (Cram- 
bus  mutabilis),  adult.    Enlarged. 


Four  species  have  thus  far  been  bred  from  corn,  namely,  Crambus 
trisectus  Walker  (Fig.  20,  21),  C.  luteolellus  Clem.,  C.  mutabilis  Clem. 
(Fig.  22,  23),  and  C.  vulgivagellus  Clem. 

Besides  the  injuries  to  corn,  grass,  and  oats  already  mentioned,  wheat 


372  BULLETIN   No.  95.  [November, 

and  rye  have  been  injured  by  vulgivagellus,  tobacco  by  luteolellus  (calig- 
inosellus),  and  cranberry  by  hortuellus,  a  species  not  yet  reported  from 
corn. 

There  are  about  sixty  species  of  the  genus  Crambus  in  the  United 
States.  So  far  as  known  they  are  of  very  similar  habit,  and  it  is  quite 
likely  that  any  of  them  living  habitually  on  grass  will  injure  corn  if  this 
is  exposed  to  their  attack.  The  species  notably  injurious  to  this  crop 
will  consequently  depend,  in  all  probability,  upon  those  which  happen 
to  predominate  in  the  grass  at  the  time  the  field  is  plowed,  and  as  these 
predominating  species  differ  from  year  to  year,  the  list  above  given  is 
not  to  be  regarded  as  final. 

Distribution. — The  recorded  distribution  of  the  four  species  actually 
bred  from  corn  extends  from  the  Atlantic  to  the  Pacific,  and  from  Maine, 
Canada,  and  California,  to  Texas,  Louisiana,  and  Florida. 

More  specifically,  the  known  distribution  of  the  species  with  which 
we  are  here  especially  concerned  is  substantially  as  follows : 

C.  mutabilis,  from  Ontario,  Massachusetts,  Connecticut,  and  Dakota, 
to  New  York,  Ohio,  Illinois,  Kentucky,  Florida,  Louisiana,  Texas, 
Nebraska,  and  California. 

C.  trisectus,  from  Canada,  Maine,  Michigan,  Minnesota,  Dakota, 
Wyoming,  and  Vancouver,  to  New  Jersey  and  New  Mexico. 

C.  luteolellus*  from  Maine,  New  York,  Ontario,  Minnesota,  and 
Colorado,  to  North  Carolina,  Illinois,  Texas,  Arizona,  and  California. 

C.  vulgivagellus,  from  Maine,  Massachusetts,  New  York,  Canada, 
Wisconsin,  and  Vancouver,  to  North  Carolina,  Missouri,  Colorado,  Utah, 
and  California. 

Life  History. — The  biology  of  the  species  has  not  been  sufficiently 
studied  to  give  us  a  comparative  knowledge  of  their  life  histories, 
although  existing  evidence  indicates  a  difference  in  the  species  with 
respect  to  the  number  of  annual  generations,  which  varies  from  one  to 
three  in  a  season  in  the  same  locality.  It  is  possible,  however,  that 
ampler  data  would  remove  this  impression. 

So  far  as  known,  all  pass  the  winter  in  our  latitude  in  the  caterpillar 
stage,  apparently  not  full  grown.  In  early  fall  they  close  the  mouths 
and  thicken  the  walls  of  their  cylindrical  silk-lined  nests  before  going 
into  hibernation.  In  the  spring  they  come  forth,  complete  their  growth, 
pupate  near  the  surface,  and  later  emerge  as  adults.  "The  eggs,"  says 
Dr.  Felt,  "are  usually,  if  not  always,  allowed  to  fall  at  random  in  the 
grass.  They  hatch  in  from  ten  to  twenty  dcys."  Eggs  of  various 
species  have  been  obtained  by  us  from  June  9  (trisectus)  to  July  22 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  373 

(hortuellus),  and  these  have  hatched  in  from  ten  to  fourteen  days.  Most 
of  them  were  laid  singly,  but  occasionally  in  clusters  of  five  or  six. 
When  first  laid  they  are  nearly  white,  but  they  change  with  age  to  yellow- 
ish orange.  The  young  caterpillars  form  their  web-lined  nests  imme- 
diately upon  or  just  under  the  surface  of  the  soil,  strengthening  them  by 
the  addition  of  bits  of  grass  or  particles  of  dirt  to  the  surface.  They 
commonly  cut  off  the  blades  of  grass  and  draw  the  ends  down  into  the 
nest  so  that  they  can  feed  without  leaving  it. 

The  data  concerning  the  life  histories  of  the  various  species  are  not 
sufficiently  complete  for  all  to  warrant  general  comparative  statements 
concerning  them.  It  is  certain  that  two  of  the  species,  trisectus  and 
mutabilis,  are  at  least  two-brooded.  A  tabulation  of  the  dates  of  collec- 
tion of  a  very  large  series  of  adults  made  in  several  successive  years, 
shows  two  well-marked  periods  of  maximum  occurrence,  one  in  July 
and  one  in  August,  with  a  comparatively  sparse  showing  towards  the 
middle  of  July.  Larvse  of  trisectus  have  been  found  abundant  in  May 
and  early  June,  and  again  in  late  July  and  early  August.  Those  of 
mutabilis  are  commonest  in  the  latter  half  of  June.  The  fact  that  a 
third  wave  of  abundance  of  the  moths  of  trisectus  was  noted  one  year  in 
early  October  suggests  the  possibility  of  a  third  brood  of  this  species  at 
least.  Vulgivagellus,  on  the  other  hand,  appears  to  be  a  single-brooded 
species.  The  larvse  mature  late  in  May,  but  remain,  as  a  rule,  in  their 
underground  cells,  like  some  cutworms,  dormant  through  midsummer, 
emerging  as  adults  in  August  and  September.  The  eggs  are  then  laid 
for  the  hibernating  brood  of  the  caterpillars,  which  will  be  found  in 
young  corn  most  abundantly  during  the  latter  part  of  May  and  early  in 
June. 

The  data  concerning  luteolellus  also  indicate,  so  far  as  they  go,  a 
single  brood,  the  moths  appearing  most  abundantly  in  June  and  July, 
with  only  scattering  occurrences  in  August,  and  none  in  "the  later  months. 
Our  breeding-cage  results  are  likewise  consistent  with  this  supposition. 

The  points  of  especial  economic  interest  in  the  life  histories  of  these 
various  species  are  virtually  the  same  as  in  the  case  of  cutworms.  It  is 
desirable  to  know  at  what  time  in  fall  the  eggs  are  laid  for  the  hiber- 
nating brood  of  caterpillars,  since  this  will  fix  the  time  when  grass-lands 
should  be  plowed  as  a  preparation  for  corn-planting  the  following  year. 
It  is  also  desirable  to  know  at  what  time  in  spring  the  hibernating  cater- 
pillars cease  their  work,  and  when  eggs  are  laid  for  the  next  generation. 
The  first  of  these  dates  fixes  the  time  of  planting  or  replanting  corn  on 
infested  land,  and  the  second  determines  when  grass-lands  may  be  plowed 
in  spring  to  the  best  advantage  if  the  sod  was  not  broken  up  the  preceding 
year. 

Prevention  and  Remedy. — The  facts  concerning  these  web-worms  all 
admonish  the  farmer  to  break  up  a  grassy  turf  as  early  in  the  fall  as 


374 


BULLETIN   No.  95. 


\November, 


practicable  preliminary  to  planting  the  ground  to  corn;  the  middle  of 
September  is  as  late  as  safety  permits.  If,  however,  this  is  not  done 
until  spring,  it  may  best  be  postponed,  so  far  as  web-worm  injury  is  con- 
cerned, in  most  cases,  until  thelatter  part  of  May.  If  an  infested  meadow 
or  pasture  is  plowed  earlier  than  this,  when  the  larvae  are  still  young, 
they  will  probably  live  to  attack  the  corn  when  it  appears ;  and  if  plowing 
is  postponed  later,  until  the  first  brood  of  moths  have  emerged,  they  are 
likely  to  lay  their  eggs  in  the  grass  before  plowing,  and  thus  to  give  origin 
to  a  brood  of  caterpillars  which,  being  quite  young  when  the  corn  comes 
up,  will  make  a  long-continued  attack  upon  it,  against  which  replanting 
will  be  of  no  avail. 


THE  BURROWING  WEB-WORMS. 

Anaphora  popeanella  Clem. 

Pseudanaphora  arcanella  Clem. 

Hypodopus  mortipennellits  Grote. 

These  species,  treated  among 
the  less  important  insects  of  the 
corn  plant,  are  mentioned  here 
merely  to  distinguish  the  larva 
of  this  group  (Fig.  24)  from  the 
other  web-worms,  which  it  re- 
sembles somewhat  in  habit  and 
injury  to  corn.  It  inhabits,  how- 
ever, a  vertical  cylindrical  bur- 
row penetrating  the  earth  to  a 
depth  varying  from  six  inches  to 
two  feet  or  even  more.  It  is 
about  the  size  of  a  common  cut- 
worm, but  differs  by  its  dull  vel- 
vety surface  and  its  colors,  vary- 
ing from  silvery  gray  to  brown, 
by  the  rows  of  polished  spots  on 
the  body,  and  by  its  greater  ac- 
tivity and  more  loosely  jointed 
.structure. 


FIG.  24.  A  Burrowing  Web-worm  (Pseuda- 
naphora or  Hypodopus).  back  and  side  views. 
Much  enlarged. 


THE  STALK-BORER. 

Papiipema  nitela  Gucn. 

(Hydrcecia  nitela,  Gortyna  nitela.) 

This  well-known  caterpillar,  often  called  the  "heart  worm"  because 
of  the  character  of  its  injury  to  corn,  may  be  at  once  known  wherever  it 
is  seen  by  tho  peculiar  break  in  the  striping  of  the  body  at  the  mid- 


1904. 


INSECT    INJURIES  TO   INDJAN    COKN. 


375 


FIG.  25.  The  Stalk-borer  (Hydrcetia  nitela) :  a,  adult;  6,  half -grown 
larva;  c,  mature  larva  in  burrow;  d.  side  of  one  of  its  segments;  e, 
pupa.  All  slightly  enlarged.  (Chittenden,  U.  S.  Dept.  of  Agriculture.) 


die  (Fig.  25,  6).  It  is  about  an  inch  long  when  full  grown.  The 
general  color  varies  from  purplish  brown  to  whitish  brown,  according 
to  age,  and  it  is 
marked  with  five 
white  stripes,  one 
running  down  the 
middle  of  the 
back,  and  two  on 
each  side.  These 
side  stripes  are 
interrupted,  being 
absent  on  the  first 
four  segments 
of  the  abdomen, 
giving  the  larva 
an  appearance  as 
if  it  had  been 
pinched  or  injured 
there.  The  stripes 
nearly  vanish 
as  the  larva  ma- 
tures (Fig.  25,  c). 

The  head  and  top  of  the  neck,  and  the  leathery  anal-shield  at  the 
opposite  end  of  the  body  are  light  reddish  yellow,  with  a  black  stripe 
on  each  side. 

Its  presence  in  a  young  stalk  of  corn  is  very  clearly  indicated  by  the 
wilting,  breaking  down,  and  death  of  the  top,  and  by  the  presence  of  a 
round  hole  in  the  side  of  the  stalk  (Fig.  25,  c),  plugged  with  the  brown 
excrement  of  the  caterpillar  within. 

It  infests  a  great  variety  of  other  plants  in  a  precisely  similar  way. 
It  is  most  noticeable  in  early  spring  in  blue-grass,  by  roadsides,  or  around 
the  borders  of  a  field,  its  presence  there  being  betrayed  by  the  whiten- 
ing of  single  heads  of  the  grass  while  all  the  rest  of  the  plant  is  green. 
At  this  time  it  is  of  small  size,  and  finds  sufficient  food  within  the  grass 
stem;  but  later  it  is  compelled  to  resort  to  thicker-stemmed  plants,  and 
it  is  at  this  time  that  it  may  appear  in  fields  of  corn. 

Going  in  usually  from  outside  the  field,  its  injury  is,  as  a  rule,  almost 
wholly  confined  to  the  outer  rows.  It  rarely  does  any  serious  general 
damage  to  corn,  although  it  is  reported  to  have  once  destroyed  fifteen 
acres  of  that  crop  near  Elmira,  Illinois,  and  it  has  also  been  occasionally 
found  injuriously  abundant  in  fields  of  wheat.  It  is  probable  that  where 
the  injury  is  not  limited  to  the  margins  of  the  field,  but  is  general  through- 
out its  area,  the  eggs  were  laid  in  fall  in  grass  or  thick-stemmed  weeds  in 
corn-fields,  where  these  have  sprung  up  profusely  after  the  corn  has  been 


376  BULLETIN  No.  95.  [November, 

laid  by.  The  burrow  which  the  stalk-borer  makes  within  the  stem  runs 
upwards  from  the  entrance  opening,  and  of  course  varies  in  size  with 
the  growth  of  the  larva.  Sometimes  in  leaving  a  stalk  it  makes  a  new 
hole  above  that  by  which  it  entered,  and  it  may  in  this  way  burrow  in 
succession  several  different  stalks  and  several  different  kinds  of  plants. 
Corn  is  injured  by  it  while  from  two  to  ten  inches  high. 

Besides  the  corn,  wheat,  and  blue-grass  already  mentioned,  it  may 
infest  oats  and  timothy,  various  garden  crops — including  potatoes, 
tomatoes,  rhubarb,  and  spinach — blackberry  and  raspberry  canes,  the 
thick-stemmed  weeds — such  as  ragweed,  burdock,  and  cocklebur — a 
considerable  variety  of  garden  flowers,  and  also  the  new  growth  of  the 
peach,  currant,  grape,  apple,  willow,  etc.  Indeed,  its  food  plants  are  so 
numerous  as  to  indicate  a  practical  indifference  to  kinds,  the  only  neces- 
sary condition  being  a  relatively  thick  stem,  soft  enough  to  allow  it  to 
enter  and  feed  freely  within.  In  the  small  grains  and  larger  grasses, 
like  oats  and  timothy,  it  makes  its  presence  manifest  by  killing  or  even 
cutting  off  the  stem  within  an  ensheathing  leaf,  thus  causing  the  head 
and  the  whole  plant  above  the  injury  to  turn  white,  and  presently  to  dry 
up.  It  is  only  one  of  several  insects  which  produce  this  general  effect 
at  this  time,  but  its  own  injury  may  be  at  once  distinguished  by  the 
round  hole  which  it  leaves  in  the  stem  of  the  infested  plant. 

It  occurs  throughout  the  United  States  and  Canada  east  of  the 
Rocky  Mountains,  but  is  most  destructive  in  our  own  latitude,  the  adult 
moth  having  been,  in  fact,  originally  described  from  specimens  sent  from 
Illinois  to  France. 

The  caterpillar,  when  full  grown,  pupates,  as  a  rule,  within  its  last 
burrow,  commonly  below  the  opening  at  which  it  entered — seemingly  a 
precaution  against  its  destruction  by  the  withering  and  breaking  away 
of  the  upper  part  of  the  injured  plant.  The  pupa  (Fig.  25,  e)  is  light 
mahogany-brown,  about  three-fourths  of  an  inch  in  length,  and  bears  at 
the  tip  of  the  body  a  pair  of  spines.  From  it  comes  out  a  fawn-gray  or 
mouse-colored  moth  (Fig.  25,  a),  with  the  outer  third  of  the  wings  paler 
and  bordered  within  by  a  whitish  cross-line.  Other  specimens  (var. 
nebris)  have  some  white  spots  on  the  disks  of  the  wings.  The  moth  is 
nocturnal,  and  has  been  taken  by  us  flying  about  electric  lights,  and  also 
at  sugar.  The  eggs  have  not  as  yet  been  found. 

There  is  but  one  brood  in  a  year,  and  by  the  end  of  June  the  cater- 
pillars are  over  half  grown,  and  have  mostly  left  the  grasses  in  which 
they  made  their  start  and  entered  the  thicker-stemmed  plants,  of  course 
including  corn.  They  live  in  this  stage  until  late  in  July,  when  pupation 
begins,  but  larvae  have  been  found  until  August  28.  The  moths  begin 
to  appear  about  the  middle  of  August,  and  continue  throughout  Septem- 
ber and  October.  They  have  never  been  found  in  hibernation,  and  it 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  377 

seems  likely  that  they  lay  their  eggs  in  fall  in  grass-lands,  and  that  these 
hatch  in  fall  or  the  following  spring. 

The  stalk-borer  is  much  infested  by  parasites,  both  dipterous  and 
hymenopterous,  access  being  got  to  the  caterpillars,  doubtless,  during 
their  intervals  of  wandering  while  outside  the  infested  plants. 

Fortunately,  injuries  by  this  insect  are  not  of  a  kind  to  require 
special  measures  of  prevention  or  remedy.  It  is,  of  course,  impossible 
to  poison  the  larva  in  the  corn-field,  and  the  breeding  habits  of  the  insect 
are  not  such  as  to  enable  us  to  destroy  it  in  the  pupa  state  by  any  ordi- 
nary operation.  If  headlands  and  other  grassy  lots  adjoining  corn 
show  in  early  spring  an  unusual  abundance  of  these  insects,  it  might  be 
worth  while  to  mow  the  infested  turf  and  carry -away  and  feed  the  cut 
grass  promptly,  before  the  caterpillars  could  escape  to  enter  the  corn. 

A  number  of  other  stalk-borers  besides  the  one  especially  referred  to 
in  this  discussion,  occur  in  Illinois,  all  closely  related  to  the  preceding, 
extremely  like  it  in  general  appearance,  and  injuring  vegetation  in  an 
identical  manner.  Their  life  histories,  so  far  as  we  may  infer  from 
scattered  observations  and  breeding-cage  notes,  are  practically  the  same 
as  those  of  the  common  species.  None  of  them  have  been  noticed  in 
corn,  although  some  of  them  may  easily  have  been  confused  with  nitela 
in  corn-field  collections.  These  related  stalk-borers  differ  from  nitela 
especially  in  the  fact  that  the  longitudinal  lines  are  less  developed  in 
some  of  the  species  and  more  so  in  others. 

THE  ARMY-WORM. 

Leucania  unipuncta  Haw. 

(Heliophila  unipuncta.} 

(Plate  II.) 

This  notorious  entomological  raider  and  marauder,  although  one  of 
the  most  destructive  of  the  insect  pests  of  American  agriculture,  is 
actually  noticed  and  distinguished  by  individual  farmers  only  when  it 
becomes  so  numerous  as  to  travel  in  companies,  that  is,  once  in  some 
ten  or  fifteen  years,  or  so,  in  any  given  locality.  Indeed,  many  Illinois 
farmers  of  several  years'  experience  have  never  seen  the  army-worm  at 
all  to  know  it,  and  many  more  would  not  recognize  it  with  any  certainty, 
if  found  within  their  fields  and  meadows,  until  it  got  practically  beyond 
control.  It  is  often  very  desirable,  however,  that  its  presence  in  grass- 
lands should  be  detected  before  it  has  begun  its  career  of  general  destruc- 
tion, and  a  good  and  plain  description  of  it  is  consequently  very  much  to 
be  desired. 

This  caterpillar  should  be  looked  for  especially  in  the  coarser,  ranker 
grass  growing  in  the  lower,  moister  parts  of  the  meadow.  In  the  lati- 
tude of  central  Illinois,  it  appears  in  three  broods  or  successive  genera- 


378  BULLETIN   No.  95.  |  November, 

tions  each  year;  the  first  about  the  middle  of  May,  the  second  during 
the  latter  part  of  June,  and  the  third  in  August  and  September.  But  one 
of  these  generations  is  seriously  injurious  during  the  same  year,  some- 
times the  first  and  sometimes  the  second,  while  the  third,  with  rare 
exceptions,  is  economically  insignificant.  The  earliest  generation  (May 
and  early  June)  is  most  likely  to  be  the  destructive  one  in  southern 
Illinois,  and  the  second  generation  (late  June  and  early  July)  in  the 
central  and  northern  parts  of  the  State.  The  third  generation  (August 
and  September)  has  never  been  injurious,  to  my  knowledge,  in  Illinois, 
but  has  sometimes  been  so  in  New  Jersey  and  New  York.  The  abun- 
dant generation  moves  in  hordes  or  "  armies  "  out  of  its  breeding  grounds 
and  into  adjoining  fields,  destroying  virtually  every  green  thing  as  it  goes. 

Description  of  the  Army-worm  (See  PI.  II). — This  caterpillar  has 
the  general  appearance  of  a  cutworm,  to  which,  in  fact,  it  is  closely 
related,  and  whose  habits  and  injuries  to  vegetation  it  imitates  in  ordi- 
nary years  when  it  is  not  unusually  abundant.  .It  is  readily  distin- 
guished, however,  from  ordinary  cutworms  by  its  much  more  distinctly 
striped  markings,  in  colors  ranging  from  light  greenish  yellow  to  greenish 
black  and  black.  Looking  at  the  side  of  the  caterpillar,  one  sees  three 
such  stripes  very  distinctly  marked,  of  which  the  central  one  is  dark, 
and  the  others  are  lighter.  The  back  of  the  caterpillar  is  greenish  black, 
and  along  the  middle  of  it  runs  a  narrow  white  stripe,  broken  and  usually 
indistinct  except  at  each  end.  Of  the  three  side  stripes,  the  lower  one, 
which  is  just  below  the  spiracles,  is  light  greenish  yellow  and  is  narrowly 
edged  with  white.  The  upper  one  is  a  little  darker,  also  edged  with 
white,  and  with  its  center  greenish  black.  The  middle  one  of  these  three 
stripes,  which  has  the  spiracles  at  its  lower  edge,  is  black,  sometimes  a 
little  lighter  along  its  center.  The  head  is  of  a  greenish  brown  color, 
with  coarse  black  mottlings,  and  with  blackish  lines  where  the  pieces  of 
the  head  seem  joined  together.  The  belly  of  the  larva  is  lighter  than 
the  back  and  more  or  less  mottled  with  blackish.  This  description 
applies  quite  closely  to  ordinary  examples,  which  the  colored  plate  in 
this  report  correctly  illustrates.  Sometimes,  however,  paler  specimens 
are  found,  in  which  all  the  colors  are  less  intense,  but  the  pattern  is 
unchanged. 

The  Army-worm  Moth  (See  PI.  II). --The  army-worm  hatches  from 
eggs  laid  by  very  common  night-flying  moths.  These  are  yellowish 
brown,  with  a  white  speck  near  the  middle  of  each  fore  wing,  as  shown 
distinctly  in  the  colored  plate.  They  are  fond  of  sweets,  and  may  be 
captured  in  large  numbers  at  night  by  using  sugary  substances  as  a  bait . 

Habits  of  the  Army-worm. — Army-worms  are  present  every  year,  and 
are  among  the  most  numerous  of  our  native  insects.  When  present  in 
only  ordinary  numbers  they  feed  singly  in  grass-lands  like  cutworms, 
remaining  hidden  during  the  day.  and  are  then  little  likely  to  be  seen. 


PLATE  II. 
The  Army-worm,  with  pupa,  moth,  and  egg. 


1904. 1  INSECT  INJURIES  TO  INDIAN    CORN.  379 

Indeed  their  stripes  and  colors  make  them  difficult  to  distinguish  among 
their  food  plants,  and  their  habit  of  dropping  when  disturbed  serves  still 
further  to  conceal  them.  Their  ordinary  injuries  thus  pass  unnoticed 
and  their  presence  undetected  unless  the  grass  is  so  badly  damaged  as 
to  turn  brown  in  patches,  when  a  close  examination  may  disclose  them 
in  their  retreats. 

Their  traveling  habit,  which  hasjjiven  themjjheir  common  name,  can 
scarcely  be  called  normal  to  the  species,  since  they  resort  to  it  only  under 
circumstances  which  are,  for  them,  little  less  than  desperate.  When, 
by  extraordinary  multiplication,  they  become  so  numerous  in  their 
breeding  ground  as  to  devour  their  own  food  supply  before  they  have 
attained  their  growth,  they  must  search  for  more  food  elsewhere. 
Unlike  many  insects  under  similar  circumstances,  they  exhibit  a  gre- 
garious habit,  and  instead  of  dispersing  separately  in  every  direction, 
as  would  seem  to  be  the  more  rational  course,  they  move  off  together  in  a 
definite  direction  in  almost  solid  phalanx,  putting  themselves  thus  to 
the  serious  inconvenience  of  traveling  great  distances  to  find  their  neces- 
sary food,  and  exposing  themselves  likewise  to  wholesale  destruction  by 
birds  and  other  enemies  and  to  wholesale  infestation  by  insect  parasites. 
Fortunately  for  agriculture,  they  likewise  expose  themselves  by  this 
same  act  to  destruction  by  the  farmer,  who  can  annihilate  a  compact 
mass  of  traveling  caterpillars  although  he  might  be  helpless  against 
their  attack  if  they  separated  and  dispersed  to  all  parts  of  the  compass. 

Feeding  ordinarily  upon  grasses,  they  prefer  these  and  grass-like 
grains,  even  on  their  desperate  marches.  They  seem  to  eat  with  almost 
equal  relish  blue-grass,  timothy,  wheat,  oats,  corn,  rye,  and  barley,  and 
will  likewise  readily  take  sorghum,  Hungarian  grass,  millet,  and  flax. 
In  confinement  they  have  grown  and  completed  their  transformations 
when  fed  exclusively  on  poppy,  beet,  lettuce,  cabbage,  raspberry,  onion, 
parsnip,  radish,  carrot,  or  pea,  but  have  declined  cotton  and  grape. 
Ordinarily  clover  is  not  eaten  by  them,  and  it  is  said  that  the  timothy  in 
a  mixed  field  is  often  eaten  to  the  ground,  leaving  uninjured  the  clover 
scattered  through  it.  A  remarkable  exception  is  reported,  however, 
from  New  Jersey,  where  in  1880  clover  was  generally  eaten  by  army- 
worms  in  some  localities.  In  the  field,  besides  the  plants  above  men- 
tioned, they  have  also  eaten  cranberry,  strawberry,  bean,  sugar-beet, 
sweet  potato,  parsley,  watermelon,  cucumber,  apple,  pepper,  honey- 
suckle, ragweed,  wild  Solatium,  and  amaranth. 

When  they  enter  a  field  of  young  corn  they  first  climb  up  the  plants, 
eating  the  blades  of  the  leaves  on  each  side  of  the  midrib,  but  presently, 
as  they  become  more  abundant,  they  may  virtually  devour  the  whole 
plant  to  the  surface  of  the  ground.  "Fully  to  realize  the  destructive 
capabilities  of  this  insect,"  says  Slingerland,  "  one  must  see  (no  descrip- 
tion will  suffice)  an  army  of  the  worms  on  the  march  and  at  work.  In 


380  BULLETIN   No.  95. 

most  cases  the  caterpillars  in  each  of  these  armies  must  have  been  num- 
bered by  the  millions;  even  an  approximate  estimate  of  the  worms  of  a 
single  army  would  have  been  impracticable.  Oftentimes  when  an  army 
was  marching  across  a  lane  or  roadway,  nearly  the  entire  surface  of  the 
ground  for  several  rods  would  be  covered  by  a  mass  of  worms;  one  could 
not  step  without  crushing  several  of  them."  They  feed  mostly  at  night 
and  on  cloudy  days,  although  not  by  any  means  refraining  from  travel 
and  feeding  in  bright  weather. 

Geographical  Distribution. — The  army-worm  is  apparently  a  North 
American  species,  and  was  well  known  in  New  England  before  the  Revo- 
lution, where,  indeed,  measures  for  the  arrest  of  its  movements  were 
adopted  which  are  still  the  best  we  can  suggest.  The  species  is  now 
distributed  throughout  nearly  the  whole  world,  but  it  is  only  in  the 
United  States  east  of  the  Rocky  Mountains  and  in  Canada  that  it  multi- 
plies to  a  number  such  as  to  compel  its  movements  en  masse  in  search  of 
food.  It  is  particularly  abundant  throughout  the  region  from  Iowa  and 
Maine  to  Texas,  Alabama,  and  North  Carolina,  and  in  this  region  there 
is  rarely  a  year  in  which  it  does  not  somewhere  become  numerous  enough 
to  do  serious  injury. 

Life  History  of  the  Army-worm. — The  yearly  history  of  the  species  is 
not  fully  known  as  yet,  some  diversity  of  opinion  prevailing  as  to  the 
stage  in  which  it  hibernates.  Many  accurate  observations  on  this  sub- 
ject relate  to  partly  grown  caterpillars  found  late  in  fall,  winter,  or  early 
spring,  and  hibernation  in  this  stage  seems  to  be  a  somewhat  general 
occurrence.  On  the  other  hand,  we  have  taken  the  moth  in  March  in 
Illinois,  and  have  once  seen  it  common  at  lights  on  April  11.  It  is 
also  said  by  Prof.  John  B.  Smith  to  have  been  found  in  New  Jersey 
during  the  entire  winter  in  sheltered  places.  We  have  seen  no  satisfac- 
tory evidence  of  its  hibernation  in  the  pupa  stage,  although  this  fact  is 
likewise  asserted  by  some. 

When  a  brood  of  the  caterpillars  becomes  full  grown  they  rapidly 
disappear,  entering  the  ground  an  inch  or  so,  and  forming  there  smooth 
cavities  by  twisting  about,  or  making  a  slight  cocoon  under  clods  or 
other  shelter.  There  they  change  to  smooth  brown  pupa?  (See  PI.  II), 
from  which  later  the  moths  emerge. 

The  eggs  for  the  first  generation  are  laid,  in  our  latitude,  about  the 
middle  of  May.  These  hatch  in  from  eight  to  ten  days.  The  life  of  the 
caterpillar  is  twenty  to  thirty  days;  that  of  the  pupa,  twelve  to 
fifteen  days;  and  the  moths  begin  oviposition  about  a  week  after  they 
emerge.  This  gives  about  seven  to  eight  weeks  for  the  life  cycle  in  mid- 
summer. The  eggs  (See  PI.  II)  are  placed  by  the  mother  moth  behind  the 
surrounding  sheath  of  the  leaf  of  grass  or  grain,  from  ten  to  fifty  or  more 
together,  imbedded  in  a  gummy  substance  which  fastens  them  also  to  the 
leaf  surface  and  closes  the  sheath  around  them.  It  is  said  that  "earlv 


1904.]  INSECT  INJURIES  TO  INDIAN  CORN.  381 

in  the  season  the  moths  prefer  to  oviposit  in  the  cut  straw  of  old  stacks, 
in  haystacks,  and  even  in  old  fodder  stacks  of  corn,  or  in  old  bits  of  corn- 
stalks scattered  about  in  pastures."  Eggs  have  also  been  found  in  the 
spring  in  young  grain.  Slingerland  reports  that  as  many  as  737  eggs 
have  been  found  in  the  body  of  a  single  moth — a  fact  which  goes  far  to 
account  for  the  tremendous  power  of  reproduction  exhibited  by  this  insect. 

Until  after  the  second  molt  the  young  caterpillars  have  the  looping 
habit  of  the  measuring-worms,  and  spin  down  at  the  end  of  a  thread 
when  disturbed,  as  do  the  canker-worms.  They  often  leave  their  feed- 
ing-grounds when  they  are  scarcely  more  than  half  grown.  They  may 
travel  at  the  rate  of  five  to  ten  rods  an  hour. 

Prevention  and  Remedy. — The  fact  that  two  successive  generations 
of  the  army- worm  are  never  injurious  hi  the  same  locality  is  due  to  the 
sudden  check  placed  upon  their  multiplication  by  a  concentration  and 
increase  of  their  enemies  of  various  kinds,  the  most  important  of  which  are 
insect  parasites  and  parasitic  diseases.  Birds  and  ground-squirrels  gather 
for  their  destruction,  but  these  larger  animal  enemies  are  rarely  numerous 
enough  to  produce  any  very  marked  effect  upon  the  traveling  horde. 
Their  insect  parasites  and  fungous  diseases,  on  the  other  hand,  presently 
come  to  affect  them  so  generally  that  they  perish  wholesale  either  before 
or  after  entering  the  ground  for  pupation,  the  soil  in  such  cases  stinking 
with  their  decayed  remains.  Parasitic  insects  have  been  seen  to  swarm 
about  them  in  such  numbers  that  the  sound  of  their  flight  was  like  that 
of  a  hive  of  bees. 

In  case  by  watchfulness  and  good  luck  a  farmer  detects  a  colony  of 
army-worms  before  it  has  left  its  native  field  of  grass  or  grain,  he  may 
to  advantage  surround  it  by  a  few  deep  furrows  so  plowed  that  the  dirt 
shall  be  thrown  inward  towards  the  colony,  and  then  either  kill  the 
caterpillars  as  they  collect  in  this  furrow  in  their  efforts  to  escape,  or 
poison  them  in  a  body  by  spraying  the  vegetation  on  which  they  feed 
with  an  arsenical  poison,  like  Paris  green. 

To  stop  them  and  destroy  them  after  they  have  taken  up  their  line 
of  march,  deep  furrows  are  plowed  in  front  of  them.  The  straight  side 
of  each  furrow,  which  should  be  the  side  away  from  the  worms,  is  trimmed, 
if  necessary,  with  a  spade  so  that  the  dirt  shall  be  perpendicular  or 
overhang  a  little,  and  post-holes  are  made  in  the  bottom  at  intervals  of 
ten  or  fifteen  feet  where  the  caterpillars  may  collect  in  quantity  as  they 
travel  up  and  down  the  furrow  seeking  to  escape.  Here  they  may  be 
readily  killed  by  pouring  a  little  kerosene  upon  the  struggling  mass  in 
each  post-hole,  after  which  they  should  be  shoveled  out  to  make  room 
for  another  collection. 

Prompt  and  vigorous  action  is  essential  to  success,  since  the  pres- 
ence of  these  insects  is  often  not  detected  until  they  are  well  under  way, 
and  their  rate  of  movement  is  such  that  acres  of  corn  may  be  sacrificed 
by  a  few  hours'  delay. 


382  BULLETIN  No.  95.  [November, 

THE  CORN  BILL-BUGS. 
Sphenophoms  parvulus  Gyll. 
S.  venatus  Say.     (S.  placidus.) 
S.  ochreits  Lee. 
S.  pertinax  Oliv. 
S.  cariosus  Oliv. 
S.  scoparius  Horn. 
S.  sculptilis  Uhl. 
S.  robustus  Horn. 

(Plate  III.) 

The  corn  "bill-bugs"  are  .snout-beetles  of  various  size  and  color 
(See  PI.  Ill,  and  Fig.  27  to  34),  but  averaging  rather  large,  the  majority 
of  them  dull  black,  with  the  surface  much  marked  with  small  pits  and 
narrow  grooves.  In  form  they  are  somewhat  irregularly  oval,  with  thick 
bodies,  rounded  above  and  beneath,  and  with  rather  long  and  thick 
"snouts"  or  "beaks"  of  medium  length,  curving  downward  from  the 
front  of  the  head.  This  so-called  snout  is  really  a  part  of  the  head  itself, 
and  bears  always  at  its  tip  a  pair  of  minute  jaws  or  mandibles,  used  in 
taking  in  food.  The  beetles  injure  and  often  kill  young  corn  in  spring 
by  thrusting  the  beak  into  the  stem  of  the  plant  near  its  base  and  eating 
out  the  inner  tissue  beneath  the  point  of  puncture.  Their  presence  in 
the  field  is  very  soon  made  manifest  by  the  appearance  of  circular  or 
oblong  holes  running  in  rows  across  the  blade  of  the  leaf,  each  row  result- 
ing from  a  single  thrust  of  the  beak  when  the  leaves  were  closely  rolled 
together  in  the  young  plant.  (See  PI.  III.)  The  injury  done  varies 
from  insignificance  up  to  complete  destruction  of  practically  every  plant 
in  several  acres  of  corn  and  for  two  or  three  successive  plantings. 

The  larvae  of  these  beetles  (See  PL  III,  and  Fig.  26)  are  rarely  found  in 
corn-fields  except  in  some  of  the  Southern  States,  where  one  of  the  species, 
robustus,  may  live  as  a  larva  in  the  pith  of  the  stalk.  The  others  feed,  in 
the  larval  stage,  so  far  as  known,  upon  the  bulbous  roots  of  grasses, 
sedges,  and  the  like,  or,  in  the  smaller 
species,  upon  the  fibrous  roots  of  the 
smaller  grasses.  These  larvae  are  thick- 
bodied,  oval,  footless  grubs,  with  hard, 
brown  or  blackish  heads,  the  first  seg- 
ment behind  the  head  being  leathery 
and  smooth  and  slightly  tinged  with 
brown.  They  are  most  frequently 
seen  imbedded  in  the  root-bulbs  of 

,•         ,i  .  ..        ,.  .  FIG.  26.  The  Corn  Bill-bug  (Sphenopfurrus 

timothy,  Or,   in  SWampy  Situations,   in        ochreus),  larva,  side  view.  Greatly  enlarged. 

the  thick  root-bulbs  of  the  common 

reed,  the  club-rush,  and  other  very  coarse  sedges  and  swamp  grasses. 


PLATE  III. 
Corn  Bill-bugs  and  larva,  with  injured  corn  plant. 


1904.] 


INSECT  INJURIES  TO   INDIAN   CORN. 


383 


FIG.  27.  Sphenophorus  parvulus, 
adult,  back  and  side  views. 
Greatly  enlarged. 


FIG.  28.    Sphenophorus  venatus,  adult, 
back  and  side  views.     Greatly  enlarged. 


FIG.  29.  Sphenophorus  ochreus, 
adult,  back  and  side  views. 
Greatly  enlarged. 


Fio.  30.  Sphenophorus  pertinax, 
adult,  back  and  side  views.  Greatly 
enlarged. 


384 


BULLETIN   No.  95. 


[November, 


FIG.  31.     Sphenophorus  cariosus,  adult,  back 
and  side  views.    Greatly  enlarged. 


FIG.  32.  Sphenophorus  scoparius. 
adult,  back  and  side  views.  Greatly 
enlarged. 


FIG.  33.  Spheturphorutacttljjtilit, 

adult,      hack      and      side      views. 
( Jreutly  enlarged. 


FIG.  34.  Sphenophorus  robvs- 
tua,  adult,  back  and  side  views. 
Greatly  enlarged. 


1904.]  INSECT  INJURIES  TO  INDIAN  COEN.  385 

Injuries  to  Corn. — With  the  exception  of  the  southern  species  men- 
tioned above,  the  injuries  to  corn  are  done  entirely  by  the  beetles,  and 
are  commonly  limited  to  the  first  year  after  grass.  In  some  cases  where 
freshly  drained  swampy  tracts  have  been  broken  up,  the  injury  may 
continue  in  diminished  quantity  the  second  year,  provided  that  the  crop 
has  not  been  sufficiently  well  tilled  to  kill  out  thoroughly  all  the  coarse 
native  sedges  and  grass-like  plants.  The  adults  of  all  the  species  feed  in 
substantially  the  same  manner,  as  far  as  observed,  and  inflict  a  similar 
injury  on  the  plants  they  infest.  Placing  itself  head  downward,  with 
its  stout  legs  embracing  and  firmly  grasping  the  stalk,  the  beetle  applies 
the  tip  of  its  beak  straight  against  the  surface,  cutting  the  outer  tissue 
with  the  jaws,  the  action  of  which  is  distinctly  audible.  Gradually,  with 
an  occasional  twisting  motion  of  the  head,  it  sinks  two-thirds  or  more  of 
its  snout  into  the  stalk,  and  then,  slightly  rolling  its  head  from  side  to 
side  with  clock-like  regularity,  it  uses  its  beak  as  a  lever  to  split  the  stalk 
and  pry  the  edges  of  the  slit  apart.  It  pauses  from  time  to  time  to  eat 
out  the  soft  tissues  within,  and  by  moving  forward  and  backward  and 
twisting  to  the  right  and  left,  it  hollows  out  an  interior  cavity  much 
larger  than  the  surface  injury  would  indicate.  Then,  pulling  the  head 
strongly  backward  with  the  compressed  beak  inserted,  the  stalk  is  split 
upward  as  a  boy  would  split  a  stick  with  a  knife.  In  this  way  a  slit  an 
inch  long  may  be  made  in  the  stalk  of  corn,  beneath  which  all  the  softer 
parts  have  been  eaten  out. 

The  injury  thus  done  varies  in  position  from  a  little  below  the  surface 
of  the  ground  to  the  middle  or  upper  two-thirds  of  the  larger  leaves. 
The  beetles  are  often  seen  at  work  on  young  stalks,  head  downward, 
with  the  beak  inserted  its  full  length.  They  are  always  on  the  lower  part 
of  the  plant,  from  an  inch  above  the  ground  to  a  little  below  it,  and  two 
or  three  of  them  are  sometimes  seen  on  a  single  stalk.  They  are  not 
easily  alarmed  when  thus  engaged,  and  a  plant  may  even  be  cut  away, 
if  care  is  used,  without  disturbing  them.  Although  they  cling  closely 
to  it,  they  can  readily  be  picked  off  with  the  fingers,  and  when  thus 
detached  they  do  not  seek  to  escape,  but  feign  death  for  a  little  time. 

The  effect  on  the  corn  plant  of  such  injuries  varies  according  to  the 
size  and  number  of  the  beetles.  A  small  species  like  the  abundant 
parvulus  (Fig.  27)  may  do  little  more  than  to  leave  a  trace  of  its  visit  in 
the  form  of  a  series  or  two  of  oblong  parallel  holes  across  one  of  the 
leaves;  but  the  larger  species,  especially  if  several  beetles  attack  the 
same  plant,  may  so  rag  and  deform  the  young  leaves  that  no  ear  is 
matured,  or  may  kill  the  plant  outright. 

While  there  is  in  Illinois  a  little  general  and  unclassifiable  injury  to 
corn  by  the  bill-bugs,  by  far  the  greater  part  of  it  occurs  under  one  of 
three  conditions.  If  swamp  lands  are  broken  up  from  grass  in  spring 
and  planted  to  corn  the  same  year,  and  especially  if  the  common  reed 


386  BULLETIN   No.  95.  [November, 

or  the  club-rush  or  other  thick-stemmed  grasses  with  bulbous  roots  are 
common  in  the  turf,  the  corn  is  extremely  likely  to  be  badly  injured  if 
not  wholly  destroyed  by  one  of  the  swamp-loving  species  of  this  group. 
If  such  land  is  poorly  cultivated,  allowing  these  bulb-root  grasses  to  grow 
up  again,  the  injury  may  continue  for  at  least  another  year.  If  an  old 
timothy-sod,  either  pure  or  mixed  with  some  other  grass,  is  plowed  in 
spring  and  planted  immediately  to  corn,  this  crop  is  likely  to  be  severely 
injured  by  other  and  smaller  species  than  those  which  attack  the  crop 
in  swamps.  I  have  known  but  one  case  of  any  considerable  injury  by 
these  insects  to  a  field  of  corn  in  Illinois,  except  under  one  of  the  above 
conditions. 

The  damage  on  swamp  sod  is  frequently  so  serious  and  extensive  as 
to  require  the  repeated  replanting  of  large  fields  of  corn.  On  timothy 
sod  it  is  not  often  so  complete,  a  badly  infested  field  rarely  having  as 
much  as  fifty  per  cent,  of  the  plants  injured,  and  these  less  seriously  be- 
cause the  bill-bugs  breeding  in  timothy  average  much  smaller  than  those 
living  in  swampy  situations. 

Injuries  to  Grass  and  Grain. — The  injury  to  timothy  meadows  by  the 
work  of  both  beetles  and  larvae  is  sometimes  considerable,  the  former 
killing  the  stalk,  and  the  latter  destroying  an  entire  stool  by  hollowing 
out  the  bulbous  root. 

In  West  Virginia,  according  to  Hopkins,  injuries  by  one  of  these 
beetles  (sculptilis)  are  among  the  prime  causes  of  the  early  decay  of 
timothy  meadows.  One  of  the  smaller  species,  parvulus  (Fig.  27),  has 
also  been  reported  as  slightly  injurious  in  the  larval  state  to  wheat,  oats, 
and  barley.  The  grub  feeds  within  the  straw  until  it  becomes  too  large 
for  its  burrow,  and  it  then  passes  to  the  roots,  often  killing  an  entire  stool 
of  grass  in  this  way. 

Distribution. — The  known  distribution  of  these  beetles  is  very  gen- 
eral throughout  the  United  States  and  Canada,  and  in  Illinois  they  may 
occur  anywhere  within  our  boundaries  if  local  conditions  permit  them  to 
breed. 

Life  History. — So  far  as  known  to  me,  all  our  bill-bugs  pass  the  winter 
in  the  beetle  stage  on  the  ground  under  rubbish  or  in  other  protected 
situations,  and  all  whose  life  history  has  been  closely  observed,  make 
their  appearance  in  spring  usually  in  fields  in  which  they  have  lived  as 
larvae,  and  where  they  have  fed  on  the  roots  of  grasses  or  grass-like 
plants  the  preceding  year.  As  the  adult  beetles  feed  on  the  same  plants 
as  their  larvae,  there  is  little  to  tempt  them  to  migrate  from  one  field  to 
another,  and  the  known  facts  clearly  indicate  that  they  pass  the  winter, 
as  a  rule,  in  the  same  fields  in  which  they  went  through  their  earlier 
stages,  provided  that  these  fields  have  been  undisturbed.  All  whose 
life  history  has  been  traced  with  sufficient  fulness  to  warrant  an  opinion 
are  apparently  single-brooded,  although  the  long  breeding  period  and  the 


1904.]  INSECT  INJURIES  TO  INDIAN  CORN.  387 

frequency,  as  a  consequence,  with  which  the  insects  may  be  found  in 
various  stages  at  the  same  time  have  sometimes  led  to  the  inference  that 
there  were  several  generations  in  a  year.  Injury  to  corn,  however,  is  in 
all  cases  limited  to  spring  and  early  summer,  ceasing  altogether  by  the 
middle  of  July  even  in  the  most  serious  cases.  Corn  not  killed  or  crip- 
pled by  these  insects  while  it  isjyoung  soon  grows  beyond  their  reach, 
and  they  then  leave  the  field  hi  search  of  more  practicable  food. 

The  eggs  of  the  Illinois  species  studied  are  laid  mainly  in  May  and 
June  in  the  roots  or  stems  of  the  plants;  larvae  may  occur  throughout 
June,  July,  and  August;  and  the  beetles  emerge  in  late  summer  and  in  fall. 

Measures  of  Prevention  and  Remedy. — Probably  no  steps  could  be 
taken  to  arrest  the  injury  to  corn  in  spring  by  these  beetles,  and  the 
only  resource  at  that  time  must  be  replanting  of  the  injured  hills.  To 
avoid  repeated  destruction,  this  should  be  postponed  as  late  as  prac- 
ticable, but  it  would  be  virtually  safe  after  the  middle  of  June.  The 
swamp  bill-bugs  are  likely  to  continue  their  destructive  work  through 
June  and  well  into  July,  and  with  them,  consequently,  this  measure 
would  usually  fail,  and  the  only  alternative  remaining  is  the  planting  of 
the  ground  to  some  crop  not  liable  to  injury  by  these  beetles.  It  appears, 
from  observations  made  in  1902,  that  injury  by  the  swamp  species  may 
be  forestalled  by  breaking  up  the  sod  in  early  fall,  and  it  has  also  been 
repeatedly  observed  that  corn  growing  upon  timothy  sod  of  early  fall 
plowing  was  relatively — usually,  indeed,  completely — free  from  bill-bug 
injury  the  following  spring. 

For  details  concerning  the  several  species  the  reader  is  referred  to 
an  article  on  the  corn  bill-bugs  published  in  my  Fifth  Report,  the  six- 
teenth of  this  office  (1890),  and  to  another  on  "The  Corn  Bill-bugs  in 
Illinois,"  in  my  Eleventh  Report — the  twenty-second  of  the  office  (1903). 

THE  CHINCH-BUG. 

Blissus  leucoptents  Say. 

(Plate  I.) 

This  notorious  insect,  one  of  the  very  worst  enemies  of  American 
agriculture,  is,  on  the  whole,  the  most  destructive  to  corn  of  all  the 
insect  species  to  whose  attack  that  crop  is  subject.  It  is  true  that  in 
some  parts  of  the  state  it  has  now  been  virtually  unknown  for  many 
years,  and  that  where  it  is  most  commonly  destructive,  periods  of  sev- 
eral years  may  succeed  each  other  with  no  noticeable  loss  to  the  corn 
farmer  on  its  account.  There  are  considerable  districts,  however,  in 
which  it  is  permanently  present  in  numbers  sufficient  to  do  every  year 
more  or  less  injury  in  corn-fields,  varying  from  what  may  be  described  as 
trifling  to  the  total  destruction  of  the  entire  crop  over  many  square  miles 
of  territory.  It  is  estimated  that  the  total  agricultural  losses  due  to  the 


388  BULLETIN  No.  95.  [November, 

ravages  of  this  insect  have  amounted  in  single  states  to  from  ten  to 
twenty  million  dollars  in  a  season,  and  throughout  the  whole  range  of 
the  insect  to  a  hundred  million  dollars  or  more  in  a  single  year. 

It  must  be  admitted,  however,  that  the  weather  conditions  under 
which  its  injuries  become  serious  are  such  that  the  corn  would  suffer 
materially  from  drouth  if  it  were  not -infested  by  chinch-bugs  at  all,  and 
as  the  effect  of  the  insect  attack  is  virtually  indistinguishable  from  that 
of  excessive  dry  weather,  it  is  usually  quite  impossible  to  separate  the 
effects  of  these  co-operating  causes.  Estimates  of  injury  by  chinch-bugs 
are  therefore  exceptionally  uncertain. 

Description  of  the  Chinch-bug. — Although  this  insect  is  so  abundant 
and  destructive  at  certain  times  and  places,  its  appearances  in  numbers 
sufficient  to  attract  attention  are  often  separated  by  intervals  of  many 
years,  and  multitudes  of  farmers  consequently  do  not  know  it  at  sight. 

When  full  grown  (See  PL  I)  it  is  readily  distinguished  from  any 
other  insect  of  its  region  by  its  size  and  form,  and  by  the  peculiar  distri- 
bution of  the  white  on  its  back.  Looked  at  from  above,  the  outline  of 
the  entire  insect  is  an  elongate  oval  with  rather  straight  sides  and 
broadly  rounded  ends.  Its  length  is  three-twentieths  of  an  inch  or  a 
little  less,  and  its  breadth  about  a  fourth  as  much.  The  head  and 
thorax  are  black,  and  all  the  surface  is  minutely  hairy  except  that  of  the 
wings.  The  wing-covers,  which  conceal  the  abdomen,  are  milk-white, 
with  a  triangular  black  scutellum  between  them  in  front,  and  a  black 
blotch  at  about  the  middle  of  each  side.  These  invasions  of  the  white 
area  give  it  roughly  the  form  of  the  letter  X,  and  this  cross  mark  of 
white  on  the  back  is  the  characteristic  mark  of  the  species.  In  winged 
specimens  which  have  recently  changed  by  molting  from  the  preceding 
stage,  the  black  of  the  above  description  is  represented  by  a  dull  pink, 
the  wing-covers,  however,  being  wholly  white,  with  pinkish  veins. 

The  chinch-bug  molts  four  times  after  hatching,  and  changes  its 
appearance  materially  with  each  molt.  There  are  thus  five  distinguish- 
able stages,  the  first  three  of  which  together  are  often  called  the  red 
stage  of  the  insect. 

In  the  first  of  the  red  stages  the  young  chinch-bug  is  pale  red 
throughout,  with  a  band  of  yellowish  across  the  base  of  the  abdomen. 

In  the  second  stage  the  red  of  the  head  and  the  prothorax  changes  to 
a  dusky  tint,  and  the  abdomen  becomes  a  bright  vermilion  with  a  pale 
yellow  band  across  its  base,  and  with  faint  dusky  patches  on  its  poste- 
rior segments. 

In  the  third  stage,  small  rounded  pads  appear  on  the  thorax,  pro- 
jecting backward  in  the  place  of  the  future  wings.  The  head  and  the 
thorax  are  wholly  black  or  dusky,  and  the  abdomen  is  a  dusky  red  with 
a  patch  of  darker  red  near  the  middle,  the  light  band  across  its  base  still 
remaining,  although  partly  concealed  by  the  wing-pads  at  its  ends. 


PLATE  I. 
The  Chinch-bug :  five  stages  of  development  and  the  egg. 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  389 

In  the  fourth  stage  the  original  red  color  has  wholly  disappeared, 
the  general  tint  varying  from  dusky  gray  behind  to  black  in  front,  with 
a  remnant  of  the  pale  band  across  the  base  of  the  abdomen  showing 
behind  the  much  enlarged  wing-pads.  This  is  sometimes  called  the  pupa 
stage,  and  is,  of  course,  the  next  preceding  that  of  the  winged  insect. 

The  egg  (See  PL  I)  is  a  very  slender  oval,  about  .03  of  an  inch 
in  length,  rather  narrowly  rounded  at  one  end,  and  slightly  docked  or 
squared  at  the  other,  where,  under  a  high  magnification,  four  small 
rounded  tubercles  may  be  seen.  Its  color  is  at  first  whitish  and  trans- 
lucent, but  later  darkens  to  amber,  and  finally,  as  the  insect  develops 
within,  becomes  definitely  red. 

Food  Plants  and  Injuries  to  Crops. — The  chinch-bug  injures  all  the 
grasses  and  cereal  crops,  but  is  strictly  limited  for  food  to  plants  belong- 
ing to  the  grass  family  and  to  certain  wild  sedges.  It  is  most  destruc- 
tive to  wheat,  and  next,  probably,  to  corn,  although  it  is  likely  to  damage 
oats  very  severely.  It  infests  the  meadow  and  pasture  grasses  generally, 
and  may  destroy  them  as  completely  as  any  other  crop;  but  owing  to 
their  perennial  growth  they  afford  in  spring  much  less  fresh  and  succu- 
lent herbage  than  the  young  and  delicate  plants  in  fields  of  corn  and 
wheat.  Where  spring  and  winter  wheat  are  grown  in  the  same  region, 
the  chinch-bug  is  more  likely  to  destroy  the  former,  mainly  because 
spring-sown  grain  is  exposed  for  a  longer  time  to  chinch-bug  attack 
before  it  is  harvested.  ~The  chinch-bug  never  injures  clover,  the  cow- 
pea,  or  any  forage  crop  which  would  not  commonly  be  recognized  as 
grass;  neither  does  it  injure  potatoes,,  beans,  or  fruiting  plants  of  any 
description. 

There  is  probably  never  a  year  in  which  the  chinch-bug  does  not 
injure  grass  or  some  cereal  in  some  part  of  its  territory.  It  is,  however, 
subject  to  very  wide  fluctuations  in  number,  becoming  at  irregular 
intervals  a  pest  of  such  frightful  character  as  to  appal  the  agriculturist, 
and  reduce  whole  districts  to  temporary  poverty.  It  has,  indeed, 
modified  in  important  ways  the  agriculture  of  large  sections  of  our 
country,  leading  to  the  permanent  abandonment  of  wheat  culture  in 
many  counties  of  Illinois,  and  forcing  in  others  the  use  of  leguminous 
forage  plants  in  place  of  the  grasses  and  a  substitution  of  orchard  culture 
for  the  raising  of  grain  and  grass. 

There  is  no  very  definite  regularity  in  the  recurrence  of  its  periods 
of  greatest  destruction.  These  are,  however,  clearly  dependent  on  the 
periodicity  of  the  weather,  injury  by  the  chinch-bug  reaching  its  maxi- 
mum after  several  dry  years,  and  being  suspended  by  the  occurrence  of 
two  or  three  wet  years  in  succession.  The  chinch-bug  period  is,  how- 
ever, less  definite  and  tangible  than  the  weather  period,  since  not  every 
such  change  in  the  weather  is  followed  by  a  notable  corresponding  change 
in  the  chinch-bug  situation.  The  rise  and  the  fall  of  a  wave  of  chinch-bug 


390  BULLETIN   No.  95.  \Norcnibcr. 

abundance  occupy  unequal  times,  the  period  of  annual  increase  being 
longer  than  the  period  of  decline.  Three  or  four  or  even  five  years  of 
notable  injury  to  crops  may  succeed  one  another,  each  worse  than  the 
preceding,  before  the  maximum  is  reached,  and  then,  within  a  year  or 
two,  hordes  of  these  insects  which  may  seem  to  have  taken  permanent 
possession  of  the  fields  and  meadows  over  an  immense  district  may 
disappear  so  completely  that  it  will  be  difficult  to  find  a  few  living 
specimens. 

The  injuries  by  this  insect  are  done  by  sucking  the  sap  from  the 
plants.  Being  without  jaws  for  biting,  it  can  only  appropriate  fluid  food 
by  piercing  the  tissues  of  its  food  plant  with  the  hair-like  stylets  of  its 
beak,  and  then  sucking  out  the  sap  from  the  lacerated  cells.  Owing  to 
its  immense  numbers,  it  may  so  rapidly  drain  a  strong  and  thrifty  corn 
plant  a  foot  or  two  in  height  that  this  will  wither  and  fall  to  the  ground 
as  if  cut  off  at  the  root. 

Life  History  of  the  Chinch-bug. — The  points  of  special  economic  inter- 
est in  the  life  history  of  the  chinch-bug  are  the  stage  and  place  of  its 
hibernation,  and  the  method  of  its  escape  from  fields  of  wheat  and  other 
grains  at  harvest-time.  It  passes  the  winter  as  a  full-grown  winged 
insect  among  the  roots  of  tufted  grasses ;  under  stones  on  grassy  knolls ; 
under  leaves,  sticks,  logs,  and  bark;  in  thickets  and  the  borders  of 
woods;  beneath  the  rails  and  boards  of  fences;  and  in  similar  sheltered 
situations.  From  these  winter  quarters  it  emerges  in  spring,  the  exact 
time  varying  according  to  the  weather,  flies  freely  about  in  every  direc- 
tion and  to  considerable  distances,  settles  most  generally  in  fields  of 
wheat,  the  young  growth  of  which  affords  it  an  abundant  and  attractive 
food,  deposits  its  eggs  there  on  the  ground  about  the  base  of  the  plant, 
on  the  roots  a  little  under  the  surface,  or  sometimes  on  the  lower  part 
of  the  plant  above  ground  (See  PI.  I),  and  presently  dies.  The  eggs 
are  thus  laid,  in  central  and  southern  Illinois,  during  the  last  days  of  April 
and  the  whole  of  May.  They  begin  to  hatch  about  the  middle  of  the 
latter  month,  and  by  the  middle  of  June  the  old  chinch-bugs  which  had 
wintered  over  are  virtually  all  gone. 

At  harvest-time  the  young  of  the  new  generation  are  in  various 
stages  of  development,  due  to  the  fact  that  the  eggs  are  laid  at  intervals 
through  a  period  of  about  a  month.  There  are  at  wheat-harvest  some 
winged  bugs  in  the  field,  but  the  great  majority  of  them  are  of  ages 
varying  from  those  just  hatched  up  to  the  stage  preceding  the  last  molt. 
Forced  out  from  these  fields  of  small  grain  by  the  ripening  of  the  plants 
and  the  consequent  pressure  of  starvation,  they  enter  fields  of  oats  and 
corn  adjoining  in  a  continuous  throng,  making  their  migration  almost 
wholly  on  foot.  They  thus  concentrate  in  overwhelming  numbers  on 
the  plants  at  the  borders  of  the  newly  entered  field,  draining  rnd  killing 
everything  as  they  go.  Tt  is  at  this  time  that  the  principal  injury  to 


1904. J  INSECT  INJURIES  TO  INDIAN   COKN.  391 

corn  is  done,  and  it  is  the  method  of  this  migratory  movement  which 
gives  us  our  special  opportunity  to  protect  the  corn  by  destroying  the 
invading  army. 

When  the  majority  of  the  brood  have  acquired  wings,  flights  of  the 
adults  occur,  resulting  in  their  dispersal  through  the  field.  The  eggs  for 
a  second  generation  are  laid  most  commonly  in  corn-fields,  particularly 
on  roots  of  grass-like  weeds  growing  among  the  corn.  This  second  gen- 
eration of  the  year  reaches  the  winged  stage  late  in  August  and  early  in 
September,  and  leaves  the  fields  in  search  of  winter  quarters  from  the 
middle  of  the  latter  month  to  about  the  middle  of  October. 

It  should  be  noted,  however,  that  none  of  these  movements  are  made 
simultaneously  by  all  the  chinch-bugs  of  a  locality.  Even  the  move- 
ment from  the  winter  quarters  is  a  gradual  one,  and  in  some  cases  the 
chinch-bugs  have  not  all  placed  themselves  for  the  laying  of  their  eggs 
before  the  oats  are  sown,  or  even  by  the  time  the  corn  is  planted. 
These  crops  are  consequently  likely  to  become  somewhat  infested  in 
spring  by  the  first  generation  of  the  year,  even  though  there  may  be  an 
abundance  of  wheat  growing  also  at  the  time. 

If  the  weather  is  very  dry  at  harvest,  and  especially  if  drouth  and 
the  abundance  of  the  bugs  have  combined  to  kill  both  grain  and  grass- 
like  weeds  by  harvest-time,  chinch-bugs  will  desert  such  fields  almost 
as  fast  as  they  can  get  out  of  them.  If,  on  the  other  hand,  the  grain 
ripens  gradually  and  normally,  and  the  stubble  is  left  with  green  weeds 
interspersed,  the  bugs  are  likely  to  linger  for  days  and  even  for  weeks 
before  the  harvested  field  is  completely  free  of  them. 

The  effect  on  corn  varies  with  the  gravity  of  the  attack.  Often  in 
the  migration  movement  every  plant  of  several  rows  next  an  infested 
field  of  wheat  or  oats  will  be  blackened  by  the  invading  hordes.  In  such 
a  case  the  corn  is  completely  killed,  and  the  bugs  move  forward  row  by 
row,  carrying  the  injury,  it  may  be,  from  one  side  to  another  of  a  field 
of  twenty  or  thirty  acres,  and  leaving  scarcely  a  living  stalk  behind. 
Where  they  are  less  abundant,  however,  they  are  commonly  to  be  found 
first  and  most  numerous  behind  the  boots  or  sheaths  of  the  leaven, 
where  they  drain  and  possibly  kill  the  lower  leaves  of  the  plant,  checking 
but  not  fully  arresting  its  growth. 

The  second  generation,  hatching  in  the  corn-field,  does  much  less 
injury  to  corn  than  the  migrating  one,  not  because  it  is  less  numerous, 
but  because  it  is  more  widely  dispersed,  and  also  because  the  corn  plant 
is  larger  and  more  thrifty  at  that  season  of  the  year,  and  can  support  a 
loss  of  sap  which  would  be  fatal  to  younger  plants. 

A  serious  minor  effect  of  chinch-bug  infestation  during  the  latter 
part  of  the  season  is  a  consequence  of  the  clustering  of  the  bugs  about  the 
base  of  the  stalk  of  corn  where  the  so-called  brace-roots  are  putting  forth. 
The  growing  tissues  at  this  point  are  then  so  drained  of  sap  that  these 


392  BULLETIN   No.  95.  [November, 

roots  do  not  develop,  and  the  corn,  lacking  their  support,  falls  to  the 
earth  in  the  first  heavy  wind,  and  often  fails  to  form  a  perfect  ear. 

Preventives  and  Remedies. — Without  attempting  to  give  in  this  special 
article  any  full  program  of  procedure  for  the  restriction  of  chinch-bug 
multiplication  or  the  protection  of  crops  against  it,  three  measures  will 
be  discussed  as  particularly  applicable  to  the  corn  crop. 

A  considerable  mass  of  evidence  has  been  accumulated,  of  both  a 
popular  and  a  scientific  character,  to  the  effect  that  the  growing  of  wheat 
is  favorable  to  the  chinch-bug.  This  is  seemingly  due  to  the  fact  that 
the  wheat  plant  offers  in  April  and  early  May  a  perfect  food  to  the 
adult,  and  likewise  to  the  delicate  young  as  they  hatch  from  the  egg, 
whereas,  if  this  crop  is  not  grown,  the  bulk  of  the  hibernating  bugs 
must  distribute  themselves  over  the  meadow  grasses,  only  the  later  ones 
establishing  themselves  in  fields  of  oats  and  corn.  The  grasses  seem  at 
this  season  of  the  year  to  afford  a  less  abundant  and  perhaps  less  nutri- 
tious food  than  does  the  young  wheat  plant,  and  general  chinch-bug 
injury  of  the  first  or  even  of  the  second  grade  is  rare  in  districts  where 
no  wheat  is  raised.  The  abandonment  of  wheat  culture  is  too  drastic  a 
measure,  however,  for  general  use,  since  it  would  result  in  the  oblitera- 
tion of  that  crop  over  a  great  part  of  the  so-called  wheat  belt  in  the 
central  and  north-central  states. 

The  hibernating  habit  of  the  insect  suggests  at  once  the  advantage  of 
what  is  commonly  known  as  clean  farming — the  destruction,  that  is,  of 
all  waste  and  rubbish  of  every  description  which  may  form  a  winter 
protection  to  hibernating  insects,  and  the  burning  over  of  all  waste 
places  and  accumulations  of  rubbish  in  early  spring  before  the  bugs  have 
scattered  abroad.  The  maintenance  of  thickets  and  of  woodlands  with 
their  coating  of  leaves  and  masses  of  fallen  brush  is  especially  favorable 
to  these  hibernating  insects,  and  an  old  rail  fence  will  afford  winter 
harborage  to  millions  of  them. 

The  main  dependence  of  the  corn  farmer,  however,  must  be  the 
destruction  of  the  bugs  as  they  seek  to  enter  his  corn  after  the  ripening 
of  the  small  grain  has  forced  them  to  migrate  in  search  of  food.  As  soon 
as  the  ripening  of  badly  infested  fields  of  small  grain  compels  the  chinch- 
bug  to  desert  them,  if  the  weather  is  dry  so  that  the  ground  may  be 
thoroughly  pulverized  and  kept  in  a  dusty  condition,  a  strip  of  ground 
six  to  ten  feet  wide  should  be  deeply  plowed  along  the  side  of  the  infested 
field  adjoining  corn.  This  strip  should  then  be  thoroughly  and  deeply 
pulverized,  first  with  a  disk  harrow  and  then  with  a  brush,  until  it  is 
reduced  as  nearly  as  possible  to  the  condition  of  dust.  Next  a  short  log 
eight  or  ten  inches  in  diameter,  or  a  triangular  trough  made  by  nailing 
two  boards  together,  and  afterward  loaded  with  stone,  should  be  dragged 
endwise  back  and  forth  in  this  strip,  the  driver  riding  the  log  or  trough 
if  necessary,  until  a  deep  groove  or  furrow  has  been  made  across  the  line 


1904.]  INSECT  INJURIES  TO  INDIAN   CORN.  393 

of  march  of  the  chinch-bug  host.  The  sides  of  the  furrow  should  be 
dressed  here  and  there  with  a  hoe,  as  may  be  needful  to  make  sure  that 
no  passageway  out  is  left  for  the  chinch-bugs  which  will  presently  accumu- 
late in  the  bottom. 

If  the  furrow  has  been  well  made,  its  dusty  sides  will  prove  impassable 
to  the  bugs  which  tumble  into  it,  especially  as  these  move  at  this  time 
almost  wholly  on  foot.  If  it  is  so  placed  that  it  is  directly  exposed  to 
the  sun,  in  very  warm  weather  the  great  majority  of  the  chinch-bugs 
caught  in  it  will  be  speedily  killed  by  the  heat,  the  youngest  succumbing 
first,  but  even  adults  finally  perishing.  Nevertheless,  to  insure  their 
destruction,  holes  a  foot  in  depth  should  be  made  in  the  furrow  with  a 
post-hole  digger  at  intervals  of  about  twenty  feet,  to  serve  as  traps  for 
the  bugs.  Here  they  will  accumulate  by  pints  and  quarts  or  even  by 
pecks  in  a  place,  according  to  the  number  in  the  traveling  horde,  and  in 
these  holes  they  may  easily  be  killed  by  pouring  a  little  kerosene  upon 
them.  The  post-hole  digger  may  be  conveniently  used  for  removing 
them  when  dead  and  for  dressing  up  the  holes  again. 

As  the  myriads  of  bugs  attempt  to  escape  from  the  furrow,  climbing 
its  dusty  wall  again  and  again  with  desperate  persistence,  they  will 
gradually  lessen  the  slope  by  dragging  down  the  dust  as  they  fall  back, 
and  some  of  them  may  thus  make  their  way  out  in  time.  It  is  conse- 
quently necessary  that  the  barrier  should  be  continuously  watched  and 
occasionally  rectified  here  and  there  with  a  hoe.  After  a  time  it  will 
perhaps  be  most  convenient  to  make  another  furrow  parallel  with  the 
first,  abandoning  the  latter  or  using  it  for'the  coal-tar  strip  presently  to 
be  described. 

This  furrow  and  post-hole  barrier  will  work  to  practical  perfection 
so  long  as  the  ground  can  be  kept  thoroughly  pulverized,  but  even  a 
slight  shower  of  rain  is  sufficient  to  destroy  it,  releasing  the  imprisoned 
chinch-bugs  and  giving  free  passageway  into  the  threatened  field.  As  a 
safeguard  against  this  contingency,  a  barrel  of  coal-tar  should  be  brought 
to  the  field,  together  with  a  watering-pot  with  a  tubular  spout,  and  a 
dipper  for  dipping  out  the  tar.  If  a  slender  line  of  coal-tar  be  poured 
along  the  bottom  of  the  furrow  or  on  a  hardened  strip  of  ground  out- 
side, it  will  serve  as  a  barrier  to  the  progress  of  the  bugs  no  less  complete 
than  that  above  described.  When  first  applied  it  will  soak  speedily 
into  the  ground,  but  a  hardened  crust  will  thus  presently  be  formed 
which  will  hold  the  tar  until  it  slowly  dries  out.  It  must  commonly  be 
renewed  about  twice  a  day.  Along  this  strip  post-holes  may  be  made 
as  before,  in  which  the  chinch-bugs  will  be  caught  even  though  the 
ground  may  be  thoroughly  wet.  A  single  man  or  boy  can  guard  from 
eighty  to  one  hundred  and  fifty  rods  of  the  barrier,  but  he  must  be  in 
the  field  early  and  late. 

This  method  may  seem  troublesome  and  costly  to  the  reader  of  this 


394  BULLETJ N    No.  95.  \Norem1n'r. 

description,  but  the  actual  expenditure  of  labor  and  money  is  practically 
insignificant  as  compared  with  the  loss  of  crops  which  may  thus  be  pre- 
vented. Such  a  coal-tar  barrier  kept  up  for  a  fortnight  will  commonly 
protect  a  field  completely,  and  the  average  cost  for  tar  at  three  dollars 
and  a  quarter  a  barrel  (the  current  price  in  southern  Illinois)  will  be 
twenty-five  cents  a  day  for  a  line  of  a  hundred  rods  in  length. 

If,  as  a  consequence  of  mismanagement  or  accident,  chinch-bugs 
succeed  in  crossing  this  barrier  or  enter  the  corn  before  it  is  made,  they 
will  accumulate  upon  the  nearest  rows,  where  they  may  be  killed  at 
slight  expense  by  spraying  or  sprinkling  the  plants  with  a  mixture  of 
kerosene  and  soap-suds  known  as  the  kerosene  emulsion.  This  is  made 
and  applied  as  follows : 

Dissolve  a  half-pound  of  soap  (hard  or  soft)  in  a  gallon  of  water  by 
boiling.  Remove  from  the  stove  and  add  two  gallons  of  coal-oil  and 
mix  thoroughly  by  pumping  this  fluid  back  into  itself  by  means  of  an 
ordinary  spray  pump.  When  the  emulsion  is  formed  it  will  look  like 
buttermilk.  To  each  quart  of  this  mixture  add  fifteen  quarts  of  water 
and  sprinkle  or  spray  upon  the  corn,  preferably  before  10  o'clock  A.  M., 
or  after  3  o'clock  P.  M.  The  bugs  should  be  washed  off  so  that  they  will 
float  in  the  emulsion  at  the  base  of  the  plant.  A  teacupful  to  a  hill  is 
generally  sufficient,  but  the  quantity  must  vary  with  the  number  of 
bugs  infesting  the  corn. 

The  cost  of  material  per  acre  of  corn  treated,  will  be  about  seventy 
cents  where  the  plants  are  practically  covered  with  chinch-bugs,  and 
about  thirty  cents  per  acre  where  it  is  moderately  infested. 

By  the  use  of  these  various  measures  corn  can  be  effectively  pro- 
tected against  chinch-bug  injury,  and  if  so  handled,  will  become  infested 
only  by  flying  bugs  which,  having  been  allowed  to  mature,  are  scattering 
over  the  country  in  search  of  food  and  a  place  of  deposit  for  their  eggs. 
Even  this  injury,  if  serious  enough  to  demand  treatment,  may  be  arrested 
by  the  use  of  the  kerosene  mixture  just  described. 

GRASSHOPPERS. 

ACRIDID.E. 

Injuries  to  corn  by  grasshoppers  are  rarely  sufficient  in  Illinois  to 
require  special  attention.  These  insects  do  not  breed  in  corn,  but  come 

into  it,  if  at  all,  from  grass-lands  near 
by.  They  first  injure  the  outer  rows 
by  eating  away  the  silks  and  kernels 
from  the  tip  of  the  ears  and  by  eating 
,  J\G- 35;  T,he  Red-}fpe.d  Grasshopper  np  ^g  blades  of  the  leaves,  sometimes 

(Melanoplus  femur-rubrum) .  Natural  size. 

devouring  the  husks  of  the  young  ear. 
The   effect  of   the    first   injury  is    to  prevent    the    fertilization  of   the 


1904. 


INSECT   INJURIES   TO    INDIAN    COKN. 


395 


FIG.  36.    The  Olive  Grasshopper  (Melanoplus  differ- 
entialis) .     Natural  size. 


kernel,  thus  blasting  the  ear.  At  long  intervals,  when  a  series  ol 
dry  years  has  favored  the  multiplication  of  these  insects,  they  become 
locally  destructive  in  midsummer  to  grass  and  small  grain,  and  later  to 
corn.  Under  these  circumstances  several  of  our  native  species  may  fly 
from  place  to  place  for  short  distances  in  considerable  swarms,  imitating 
in  a  small  way  the  habits  of  the  notoriously  destructive  Rocky  Mountain 
locust.  This  latter  species  does  not  occur  in  Illinois,  and  no  grasshopper 
injury  to  which  we  are  subject  approximates  that  which  sometimes 
overtakes  the  agriculturist  of  the  Western  States.  Our  Illinois  grass- 
hoppers are  subject  to 
destruction  by  a  multi- 
tude of  enemies,  which 
become,  of  course,  more 
numerous  as  the  grass- 
hoppers themselves  in- 
crease in  number.  As  a 
consequence,  two  "grass- 
hopper years,"  so  called,  rarely  succeed  each  other  in  the  same  locality. 
The  standard  means  for  destroying  grasshoppers  has  been  until 
quite  recently  the  use  of  a  long,  narrow,  shallow  pan  or  tray  of  sheet- 
iron,  commonly  called  a  "hopper-dozer,"  with  a  high  back  of  iron  or 
cloth,  dragged  across  the  field  by  hand  or  by  horse-power,  after  a  little 
kerosene  has  been  placed  in  the  bottom  of  the  pan.  Recently,  however, 
a  poison  mixture  particularly  'attractive  to  grasshoppers  is  taking  the 
place  of  this  apparatus,  and  is  doubtless  more  likely  to  be  used  in  Illinois 
wherever  active  measures  against  these  insects  are  found  necessary. 

This  mixture,  known  as  the  Griddle  mixture,  is  composed  of  one  part, 
by  measurement,  of  Paris  green  to  120  parts  of  horse  droppings,  prefera- 
bly fresh ;  or  about  a  pound  of  Paris  green  to  half  a  kerosene  barrel  of  the 
droppings,  with  a  pound  of  salt  additional  if  the  material  is  not  fresh. 

Enough  water  is  added  to 
make  the  mixture  soft  without 
being  sloppy,  and  it  is  then 
scattered  about  the  field  in 
quantities  according  to  the 
number  of  the  insects  which 
will  be  attracted  to  it  for  a 
distance  of  forty  feet.  This 
poison  is  most  effective  when 
fresh,  but  it  will  do  excellent  work  when  several  weeks  old. 

In  speaking  of  the  use  of  the  Griddle  mixture,  Dr.  Fletcher,  Dominion 
Entomologist  of  Canada,  says :  "  In  this  section  all  used  the  poison  and 
only  a  few  acres  of  crops  were  destroyed.  I  am  convinced  that  had  we 
begun  the  test  earlier,  hardly  a  bushel  of  grain  would  have  been  lost. 


FIG.  37.  The  Two-striped  Grasshopper  (Melano- 
pltts  bivittatus).  Natural  size.  (Riley,  U.  S.  Dept.  of 
Agriculture.) 


396  BULLETIN   No.  95.  [November, 

It  is  not  exaggerating  to  say  that  dead  locusts  could  be  gathered  up  in 
wagon-loads,  and  at  times  be  smelt  a  half-mile." 

The  ordinary  method  of  making  and  using  the  hopper-dozer  is  thus 
given  in  the  Third  Report  of  the  State  Entomologist  of  Minnesota,  that 
for  1897: 

"A  sheet  of  ordinary  sheet-iron,  such  as  is  used  for  making  stove- 
pipes, is  turned  up  one  and  a  half  inches  around  the  edges  and  riveted  at 
the  corners.  This  makes  a  shallow  pan  about  eight  feet  long,  two  feet 

broad,  and 
one  and  one- 
half  inches 
deep.  To  the 
bottom  of 
this  are 
riveted  six 
small  strips 
which  can  be 

FIG.  38.    The  Bird  Grasshopper  (Schistocerca  americana).   Slightly  enlarged. 

fastened     to 

the  three  runners  on  which  the  pan  rests.  To  the  rear  side 
of  the  pan  is  screwed  a  light  wooden  frame,  as  long  as  the  pan  and 
one  and  one-half  feet  high.  Over  this  frame  a  piece  of  canvas 
is  stretched.  This  frame  serves  the  important  office  of  throwing  back 
all  those  locusts  that  otherwise  jump  clear  over  the  pan,  and  to  throw 
them  into  the  oil.  The  runners  on  which  the  pan  rests  are  usually  made 
from  saplings  or  small  pieces  of  boards  having  an  upward  curve  in  front 
to  prevent  them  from  catching  in  the  ground.  The  front  ends  of  the 
runners  are  all  fastened  by  screws  to  a  cross-piece,  which  is,  in  turn, 
drawn  by  two  ropes,  one  at  each  end.  These  ropes  are  joined  in  front 
and  fastened  to  a  singletree.  Sometimes  two  hopper-dozers  are  fastened 
to  a  long  pole  by  means  of  short  ropes;  this  is  very  easily  drawn  by  one 
horse.  Just  in  front  of  the  pan  is  fastened  a  piece  of  rope  which  sweeps 
the  ground  a  few  inches  in  advance  and  serves  to  stir  up  the  hoppers  and 
make  them  jump  into  the  pans.  In  the  pan  is  laid  a  piece  of  cloth, 
which  is  first  thoroughly  saturated  with  water.  About  a  pint  of  kero- 
sene oil  is  then  thrown  in  and  the  upright  sheet  or  sail  of  canvas  is  also 
moistened  with  it.  The  machine  is  drawn  over  the  fields  or  wherever 
the  locusts  are  thickest.  In  a  short  time  it  is  usually  partially  filled 
with  dead  or  dying  insects. 

"The  slightest  touch  of  kerosene  oil,  either  from  the  pan  or  from  the 
canvas  sheet  behind  it,  means  death  to-  the  locust,  for  the  oil  spreads 
over  its  body  in  the  same  way  that  a  single  drop  of  it  will  spread  over  a 
large  surface  of  water.  ...  A  very  large  proportion  of  the  locusts 
that  come  in  contact  with  the  oil  in  the  pan  immediately  jump  out  again, 
but  they  invariably  die  in  the  course  of  a  few  seconds  or  minutes." 


PLATE  IV- 

The  Corn  Worm :   light  and  dark  individuals,  pupa,  moth,  and  egg,  with 

injured  ear  of  corn. 


1904.]  INSECT  INJURIES  TO   INDIAN  CORN.  397 

The  various  species  of  grasshoppers  injurious  to  corn  in  Illinois  are 
so  similar  in  their  habits  and  life  history  that  it  is  not  necessary  for  any 
practical  purpose  to  distinguish  them,  but  all  may  be  treated,  so  far  as 
the  corn  crop  is  concerned,  as  a  single  economic  group.  It  may  be  of 
some  interest  to  know,  however,  that  the  most  abundant  species  in  corn 
is  the  red-legged  grasshopper  (Melanoplus  femur-rubrwn,  Fig.  35), 
everywhere  the  commonest  of  its  family  in  this  state.  With  it  is  ordi- 
narily associated  the  heavier  and  more  sluggish  olive  grasshopper 
(M.  differenticdis,  Fig.  36),  with  a  sprinkling  of  the  two-striped  grass- 
hopper (M.  biviUatus,  Fig.  37).  In  the  southern  part  of  the  state  the 
lesser  migratory  locust  (M.  atlanis)  and  the  large  conspicuous  bird 
grasshopper  (Schistocerca  americana,  Fig.  38)  also  become  abundant, 
and,  like  the  species  femur-rubrum,  sometimes  collect  in  considerable 
swarms  and  make  short  flights  across  the  country. 

THE  EAR-WORM  OR  CORN-WORM. 

Heliothis  armiger  Hiibn. 
(Plate  IV.) 

This  insect,  known  also  as  the  cotton  boll-worm,  the  tobacco  bud- 
worm,  the  tomato-worm,  etc.,  is  a  slender,  nearly  hairless  caterpillar 
(See  PI.  IV),  an  inch  and  a  half  to  two  inches  long,  varying  in  color 
from  light  green  to  brown,  and  marked  with  alternating  light  and  dark 
stripes  and  lines  running  lengthwise  of  the  body.  A  common  type  has 
a  dark-brown  stripe  down  the  middle  of  the  back,  with  a  fine  white  line 
in  its  center,  and  bordered  on  each  side  by  a  pale  brown  stripe,  and 
below  the  latter  a  distinct  whitish  stigmatal  stripe.  Inconspicuous 
shining  tubercles,  each  bearing  a  delicate  hair,  are  arranged  in  transverse 
rows  on  each  segment  of  the  body.  The  head  is  amber-yellow,  and  the 
legs  are  dark. 

As  an  ear- worm  this  caterpillar  feeds  on  the  corn  beneath  the  husk, 
from  the  time  the  ear  is  formed  until  after  it  is  thoroughly  ripe,  and  it 
also  eats  the  husk,  the  leaf,  the  tassel,  and  the  tender  stalk.  Although 
it  probably  prefers  corn  to  any  other  of  its  food  plants,  it  is  likewise  fond 
of  cotton,  tobacco,  beans,  and  the  fruit  of  the  tomato,  and  feeds  freely 
upon  a  great  variety  of  other  plants,  including  pumpkin,  squash,  peanut, 
pea,  cow-pea,  hairy  vetch,  pepper,  okra,  jimson-weed  (Datura),  aspara- 
gus, ground-cherry,  hemp,  morning-glory,  gladiolus,  mallow,  mignonette, 
geranium,  sunflower,  poppy,  and  peach.  It  sometimes  devours  soft- 
bodied  insects,  such  as  the  cabbage-worm  and  cotton- worm,  and  has 
been  known  to  eat  the  young  of  its  own  kind  even  when  vegetable  food 
was  plentiful.  As  a  bean  insect  its  injuries  in  the  South  are  of  the  most 
serious  character,  whole  crops  being  destroyed,  and  it  is  also  one  of  the 
standing  and  most  destructive  pests  of  cotton  and  tobacco.  In  the 


398  BULLETIN  No.  95.  [November, 

truck-garden  its  injuries  to  green  tomatoes  are  notorious,  although  in 
this  work  it  is  aided  by  a  number  of  other  kinds  of  caterpillars. 

It  is  a  cosmopolitan  insect,  being  now  found  in  virtually  every  part 
of  the  world.  It  is  very  common  in  Illinois,  where  it  is  most  widely  known 
because  of  its  injuries  to  green  corn  in  the  garden  and  to  field  corn, 
particularly  in  the  southern  half  of  the  state. 

Early  in  spring  it  feeds  on  corn  leaves,  filling  them  full  of  holes 
the  size  of  small  shot,  and  later  in  the  season  it  enters  the  tips  of  the  ears, 
gnawing  away  the  silk  and  eating  out  irregular  winding  channels  among 
the  soft  kernels,  thus  often  making  its  way  down  below  the  middle  of 
the  ear.  A  single  caterpillar  does  not  confine  itself  to  a  single  ear,  but 
leaves  its  work  of  destruction  to  be  continued  by  other  insects  and  by 
fungi,  which  are  likely  to  follow  up  its  injuries.  It  bores  a  round  hole 
through  the  husk  at  the  side  of  the  ear,  and  infests  others  in  succession. 
There  are  sometimes  two  or  three  caterpillars  in  the  same  ear,  but  in  that 
case  they  are  commonly  of  different  ages. 

There  are  three  annual  generations  of  these  caterpillars  in  the  North, 
and  in  the  South  from  four  to  six,  besides  a  series  of  broods  preceding 
these,  which  come  from  a  few  individuals  that  pass  the  winter  as  adults. 
The  species  hibernates  in  the  pupa  stage,  and  emerges  to  lay  eggs  in 
early  April.  These  range  from  two  hundred  to  five  hundred  in  number 
for  each  female,  and  are  shaped  like  an  inverted  teacup  (See  PI.  IV), 
with  the  vertical  ribs  converging  towards  the  apex  and  broken  up  by 
concentric  grooves  into  little  knobs.  The  caterpillars  reach  their  growth 
in  from  two  to  four  weeks,  and  the  moths  (See  PI.  IV)  appear  about  two 
or  three  weeks  later.  The  first  brood  of  caterpillars  in  Illinois  feeds  on 
the  leaves  and  the  tender  shoots  of  corn,  the  second  brood  devours  the 
tassel,  the  silk,  and  the  ear,  and  the  third  infests  the  hardened  ear..  The 
fourth  and  fifth  broods,  where  they  occur,  all  attack  various  plants, 
particularly  the  cotton-boll  in  the  South.  A  sixth  generation  is  reported 
from  Texas.  The  caterpillar  enters  the  earth  for  pupation  to  a  depth 
of  from  two  to  five  inches,  where  it  forms  a  slender  cocoon  by  lining  the 
end  of  the  burrow  with  a  few  threads  of  silk  (See  PI.  IV). 

The  mastery  of  this  pest  in  the  corn-field  is  still  an  unsolved  prob- 
lem. It  is  believed  that  late  fall  plowing  of  corn-fields  which  have  been 
infested  by  this  insect  will  destroy  it  in  the  pupa  stage  by  breaking  up 
its  underground  shelter  and  exposing  it  to  the  vicissitudes  of  the  weather. 
It  is  not  often  practicable,  however,  to  plow  corn  ground  in  fall  in 
Illinois,  and  the  effect  of  such  a  measure  at  best  can  only  be  to  diminish 
the  number  of  moths  in  the  neighborhood  the  following  year. 


PLATE  V. 


THE  WHITE  GRUB.     BEETLE,  EGG,  LARVA  AND  PUPA. 
ENLARGED  2%  DIAMETERS. 


1904.]  INSECT  INJURIES  TO  INDIAN  COEN.  399 

THE  MORE  IMPORTANT  INSECTS  INJURIOUS  TO  THE 
SEED  AND  ROOTS. 

The  following  insects  injurious  to  the  seed  and  roots  of  Indian  corn 
and  belonging  in  this  section  of  "the  more  important  species,"  have  been 
treated  at  length  in  the  Eighteenth  Report  of  this  office,  published  in 
1894  as  an  appendix  to  the  Report  of  the  State  Department  of  Agri- 
culture, and  also  in  Bulletin  44  of  the  Illinois  Agricultural  Experiment 
Station,  printed  in  May,  1896: 

Wireworms  (Elateridce).     18th  Rep.,  pp.  28-51 ;  Bull.  44,  pp.  224-233. 

The  White  Grubs  (Lachnosterna  and  Cydocephala).  18th  Rep.,  pp. 
109-145;  Bull.  44,  pp.  257-280.  (See  last  plate.) 

The  Northern  Corn  Root- worm  (Diabrotica  longicornis).  18th  Rep., 
pp.  154-165;  Bull.  44,  pp.  287-296. 

The  Southern  Corn  Root-worm  (Diabrotica  12-punctata').  18th  Rep., 
pp.  146-154;  Bull.  44,  pp.  282-287. 

The  Corn  Root-Aphis  (Aphis  maidi-radicis) .  18th  Rep.,  pp.  58-85; 
Bull.  44,  pp.  237-256. 


UNIVERSITY  OF  ILLINOIS-URBANA 


